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1. INTRODUCTION

This is the second volume of an extensively rewritten,revised, and updated version of the original FAO Catalogueof Sharks of the World (Compagno, 1984). It covers all the

described species of living sharks of the ordersHeterodontiformes, Lamniformes, and Orectolobiformes,including their synonyms as well as certain well-established butcurrently undescribed species (primarily Australian speciesmentioned by Last and Stevens, 1994). It includes species ofmajor, moderate, minor, and minimal importance to fisheries(Compagno, 1990c) as well as those of doubtful or potential useto fisheries. It also covers those species that have a research,recreational, educational, and aesthetic importance, as well asthose species that occasionally bite and threaten people in thewater and the far more numerous species that are ‘bitten’ andthreatened by people through exploitation and habitatmodification. The Catalogue is intended to form part of acomprehensive review of shark-like fishes of the world in a formaccessible to fisheries workers as well as researchers on sharksystematics, biodiversity, distribution, and general biology. It alsocaters to other researchers that need comparative informationon sharks, people who encounter sharks during the course ofwork or play in the sea or in fresh water, and the general public.This Catalogue builds on a progressive increase in ourknowledge of shark biology over the past two decades, andaddresses an exponential increase in popular interest in sharksand a growing concern over their burgeoning conservationproblems.

The term Shark is used here in the broad sense of the FAOInternational Plan of Action for the Conservation andManagement of Sharks (FAO 1999). Sharks include rays orbatoids and chimaeroids as well as ‘nonbatoid’ or ‘typical’sharks, which are the subject of the original shark catalogueand of the present volume. A problem with sharks is thatmost researchers, much less the general public, areunaware of their diversity and tend to focus on the larger,toothy, nonbatoids. There are approximately 1 200 knownliving and valid species of shark-like fishes, cartilaginousfishes, or chondrichthyans, which form the classChondrichthyes. These include at least 50 species of ghostsharks, silver sharks, elephant fish, chimaeras or ratfish(order Chimaeriformes), over 600 species of batoids, flatsharks, or winged sharks (order Rajiformes), and nearly 500species of nonbatoid, ordinary or traditional sharks. Theliving shark-like fishes are included in 10 orders, 60 families,and 186 genera. Diversity of all cartilaginous fishes, livingand extinct, is far greater, with at least 140 valid families, 600valid genera, and at least 3 700 valid species (fromdatabases prepared by the writer).

The living cartilaginous fishes are divided into twosister-groups with a long separate, pre-Devonian history, thechimaeroids, Holocephali (with a single living orderChimaeriformes), and the sharks and rays proper orElasmobranchii, with the surviving group subcohortNeoselachii or modern sharks including all of the livingspecies. There is a traditional concept in the taxonomicliterature that divides the living Neoselachii into sharks,Selachii or Pleurotremata, and rays or batoids, Batoidea orHypotremata. Modern cladistic classifications rank thebatoids as an order Rajiformes of the squalomorph sharks(superorder Squalomorphii), and a sister-group of thesawsharks (order Pristiophoriformes) (Fig.1). Hence thebatoids are highly modified, highly diverse, and extremelysuccessful sharks that outnumber all other cartilaginousfishes in species. Chimaeroids are the closest evolutionary

cousins to elasmobranchs within the Chondrichthyes, andmay find a higher profile as silver sharks or ghost sharks.Considering them as ‘sharks’ brings batoids andchimaeroids out of the perceptual dark. The batoids andchimaeras tend to receive far less attention than nonbatoidsharks in most places. Some of the batoids currently are asimportant for fisheries or more so than nonbatoid sharks orchimaeroids, and some are under severe threat fromoverexploitation and habitat modification (i.e. sawfishes,freshwater stingrays). The batoid sharks will hopefully bethe subject of a forthcoming and much overdue FAOCatalogue of Batoids of the World; likewise for thechimaeroids.

The original 1984 FAO Shark Catalogue was in one volumein two parts, with pagination across both parts and with asingle bibliography. As the new Catalogue has grown apacewith new information and revisions, it is being published asthree free-standing volumes, each with separate pagination,introduction, terminology, systematic sections, glossary, listof species by FAO Statistical Areas, and a dedicatedbibliography. This will allow readers to independently useeach volume without having to consult the other volumes fortechnical terms and measurements or bibliographicpurposes, as was the case in the old catalogue. We hopethat this added flexibility will be received as an improvement.A larger general introduction to the whole catalogue appearson the first volume and appendices on shark encounters andshark conservation are confined to the third volume.Readers are also encouraged to consult the addendasection included in the last volume of the catalogue. Thepresent and second volume reviews all the species of livingbul lhead, mackerel and carpet sharks (ordersHeterodontiformes, Lamniformes and Orectolobiformes),that is, the noncarcharhinoid galeomorph sharks (see Planof the Catalogue below). The first volume covers thenonbatoid squalomorph sharks (orders Hexanchiformes,Squaliformes, Squatiniformes and Pristiophoriformes), andthe third volume reviews the carcharhinoid galeomorphs(order Carcharhiniformes).

Apparently sharks are extremely popular at present withconservationists, fisheries managers, the news andentertainment media, and the general public, and are likelyto stay that way for the foreseeable future. Negativeconcepts of sharks were reflected in the 1984 catalogue,sometimes embarrassingly so in hindsight, and partially dueto the negative shark milieu of the times. Hopefully thepresent version departs from this perspective and portrayssharks as a major group of biologically interesting, poorly

Sharks of the World, Vol. 2 1

Fig. 1 Cladogram showing interrelationships of theorders of living cartilaginous fishes

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known vertebrates with over 400 million years of unqualifiedsuccess as predators and survivors of mass extinctions.Sharks were then and are now challenged by the ultimateand most terrible of predators, Homo sapiens (‘man, prudentor wise’ as optimistically named by Linnaeus, 1758); butunlike former times the human superpredator is apparentlyaware of the problems and is taking some steps (at last!) tosolve it. One can hope that those efforts are successful.

1.1 Plan of the Catalogue

This Catalogue is based on original work on various groupsof sharks as well as my interpretation of data in the literature.Original descriptions of shark species and other taxa wereconsulted if at all possible; when not, various authoritativeworks were consulted for consensus on citations. Some ofthe arrangements of families, genera and species used heredisagree with those of previous workers including those inmy own papers, but in such cases the disagreements arediscussed or reference is made to discussions of suchproblems in the literature. Nonsystematists may notappreciate changes to classification and nomenclaturewrought by systematic studies, and often consider them asannoyances, but shark systematics evolves as does anyother science and changes are inevitable. Hopefully theyare producing increased stability as knowledge improves ina former backwater of systematic ichthyology.

Classification and systematic arrangement used here.The present arrangement has evolved from my earlier works(Compagno, 1973, 1977, 1979, 1982, 1984, 1988, 1999),which initially divided the nonbatoid sharks into eight majorgroups or orders and the batoids into four or five orders. Therelationships of the nonbatoid shark orders to one anotherother and to the batoids (order Rajiformes) is approaching atentative consensus following the work of Compagno (1977,1988, 1999 and unpublished), Shirai (1996), and deCarvalho (1996). The following classification of shark-likefishes to order is used in this work and reflects a tentativecladogram based on a summary of previous work andanalysis in progress (* starred orders are covered in thisvolume):

Class Chondrichthyes (cartilaginous fishes)Subclass Holocephali (chimaeras and fossil relatives)

Order Chimaeriformes (chimaeras or silversharks)

Subclass Elasmobranchii (sharks)Cohort Euselachii (modern sharks and fossil relatives)

Subcohort Neoselachii (modern sharks)Superorder Squalomorphi (squalomorph sharks)

Order Hexanchiformes (cow and frilledsharks)

Order Squaliformes (dogfish sharks)Order Squatiniformes (angel sharks)Order Pristiophoriformes (sawsharks)Order Rajiformes (batoids)

Superorder Galeomorphi (galeomorph sharks)Order Heterodontiformes (bullhead sharks)*Order Lamniformes (mackerel sharks)*Order Orectolobiformes (carpet sharks)*Order Carcharhiniformes (ground sharks)

Orders are the highest taxonomic groups dealt with here,and many of their synonyms are listed even though thepresent International Code of Zoological Nomenclaturedoes not treat groups higher than the family-group level(superfamilies, families, subfamilies, tribes, etc.). The

nomenclature for orders is modified from that of Compagno(1973, 1984, 1999), with synonyms listed from oldest tonewest. The orders are suffixed with -iformes followingcommon ichthyological practice at present. Families aresuffixed with -idae, the universal ending for zoologicalfamilies. Other levels between orders, families, genera andspecies are mostly not covered here. Subgenera arediscussed under their appropriate genera but species arenot grouped under subgenera and given parentheticalsubgeneric names such as Somniosus (Rhinoscymnus)rostratus, even where subgenera are considered valid, soas not to eliminate the utility of listing species alphabeticallywithin genera. Subspecies are listed in the synonymies oftheir species but are not given separate coverage.

Valid families, genera and species are provided withcitations for their author or authors, year of publication,reference and pagination (illustrations also included forspecies), while synonyms are similarly cited except for theirreferences (which are listed in the bibliography). Othercombinations of genera and species that have been used inthe literature but are at variance with valid names are citedwith author and date only. The bibliography covers a wideselection of references used in writing the catalogue, but isnot intended to be all-inclusive.

The information pertaining to each family, genus andspecies is arranged in the form used in the first edition of thisCatalogue (Compagno, 1984), with some modifications:

Family accounts include the valid modern form of thefamily name with author and year; the original citation of thefamily name with its author, year, reference and pagination;the valid type genus with author and date; the number ofrecognized genera in the family; the FAO family vernacularnames in English, French and Spanish; family Synonymswith name, author, year, and pagination; Field Marks andDiagnostic Features of members of the family; an account ofthe natural history of the family under separate sectionscovering Distribution, Habitat and Biology; a section onInterest to Fisheries and Human Impact, a synopsis of thehuman issues affecting shark families; Local Names whenavailable; a Literature section covering references to theentire family; a Remarks section mostly with systematiccomments; and a Key to Genera, when families have morethan one genus.

Generic accounts include the valid modern form of thegenus name with author and year; the original citation of thegenus or subgenus, with its author, year, reference andpagination, and, if a subgenus, the original genus name withauthor and year that the subgenus was originally placed in;the type species and means of designating it (for example,by original designation, monotypy, absolute tautonymy, orsubsequent designation); the number of recognized speciesin the genus; the synonyms of genera, with their rank(genus, subgenus, or other genus-group ranking such asW.H. Leigh-Sharpe’s ‘pseudogenera’), author, year,pagination, and genus they were described in if originallyranked as subgenera or equivalents; FAO Names if theyexist; sometimes Field Marks if genera are large anddistinctive; Diagnostic Features of the genus; a Key toSpecies if the genus has more than one species (is notmonotypic); and a Remarks section where necessary.

Species accounts include the valid modern names of thespecies, with author and date; the original citation of thespecies (or subspecies), with its author, year, reference

2 FAO Species Catalogue for Fishery Purposes No. 1

pagination; the holotype, syntypes, lectotype or neotype ofeach species (paratypes are not listed in the presentaccount), including the total length and sex of the specimen,its institutional deposition, and its catalogue number; thetype locality including the location, coordinates and depth ifavailable, where the holotype, syntypes, lectotype orneotype were caught; Synonyms of the species, includingtheir names, authors and dates; a section listing otherscientific names recently in use; the English, French, andSpanish FAO Names for the species; a lateral viewillustration, and often other useful illustrations (lateral viewdrawings are given of each shark species, usually ventralviews of heads, and often teeth and denticles of the shark inquestion); Field Marks; Diagnostic features (except inmonotypic genera); Distribution, including a map; Habitat;Biology; Size; Interest to Fisheries and Human Impact;Local Names when available; a Remarks section whennecessary; and Literature.

Synonyms include only true taxonomic synonyms of thevalid family, genus and species given. For species, anothercategory, Other Combinations, is provided for commonmisidentifications of a given species with another, validspecies (for example, Carcharhinus brachyurus was oftentermed C. remotus, but the latter is a junior synonym of C.acronotus) as well as commonly used combinations thatplace a valid species in different genera (for example,Odontaspis taurus or Eugomphodus taurus for Carchariastaurus).

FAO Family and Species Names. English, French andSpanish names for each family and species, primarily foruse within FAO, were selected by the following criteria: (a)each name applies to a single family or species worldwide;(b) the name conforms with FAO spelling nomenclature; (c)the name conforms to prior usage when possible. FAOnames are not intended to replace local species names, butare necessary to overcome the confusion caused by the useof a single name for more than one species or severalnames for one species. The FAO names used here conformwith prior FAO usage and when possible and appropriatenational and international checklists and reviews of speciessuch as Whitley (1940), Fowler (1966-1970), Shiino (1972,1976), Hureau and Monod (1973), Smith (1975), Robins etal. (1980, 1991a, b), and Lindberg, Heard and Rass (1980).The French names were selected jointly with Dr J.C. Quéro,Institut Scientifique et Technique de Pêches Maritimes,Ministère de la Marine Marchande, La Rochelle, France,and for recently discovered species with Dr B. Seret,Museum National d’Histoire Naturelle, Paris. Whenpossible, the names selected correspond to official Frenchspecies nomenclature established by the Direction desPêches Maritimes. The selection of Spanish namespresented considerable difficulties due to the lack ofdenominations for many species. Wherever possible, the“official” Spanish names adopted by F. Lozano in his book“Nomenclature ictiologica”, Madrid, 1963, were used, alongwith names for additional species coined by Dr R. Bonfil,Fisheries Centre, University of British Columbia, Vancouver.

The broader use of ‘shark’ here for all living cartilaginousfishes is noted above. The term ‘shark’ is broadly andpopularly used as a catchall term in English for all livingmembers of the Class Chondrichthyes that are not batoidsor chimaeras, although guitarfishes (Rhinobatidae) are alsotermed ‘sand sharks’, chimaeras are termed ‘ghost sharks’or ‘silver sharks’, and even certain aquarium teleosts (someloaches, Cobitidae) are termed ‘sharks’. The French ‘requin’and Spanish ‘tiburón’ are comparable general terms to

‘shark’. Several names not incorporating ‘shark’ or itsFrench or Spanish equivalents are mostly used only forsharks and not for other fishes; these include the English‘dogf ish’ , ‘smoothhound’, ‘ tope’, ‘porbeagle’ and‘hammerhead’. However, ‘freshwater dogfish’ is a regionalname for the bowfin, Amia calva, in the USA. ‘Wobbegong’is adapted from an Australian Aboriginal term for sharks ofthe genera Eucrossorhinus, Orectolobus and Sutorectus).French ‘roussette’, ‘emissole’, ‘renard’, ‘milandre’,‘marteau’, and ‘griset’, and Spanish ‘gato’, ‘cazón’, ‘tollo’,‘pintarroja’, ‘tintorera’, and ‘cornuda’, are similar terms forcertain kinds of sharks.

Usage of local names for different kinds of sharks variesfrom country to country. ‘Catshark’ is used for members ofthe Scyliorhinidae and sometimes related families (such asProscylliidae) in the United States, but also for variousorectoloboids in Australia. ‘Dogfish’ is variably used formembers of the families Squalidae (‘spiny dogfishes’),Scyliorhinidae (especially Scyliorhinus), and Triakidae(‘smooth dogfishes’, Mustelus spp.). ‘Sand shark’ may referto Odontaspididae (especially Carcharias taurus, the ‘sandtiger shark’ of the eastern USA, called ‘ragged-tooth shark’in South Africa and ‘grey nurse shark’ in Australia), toTriakidae (especially to Mustelus spp.) off the western USA,or guitarfishes off South Africa. In the present Catalogue‘catshark’ is restricted to members of the Scyliorhinidae andProscylliidae (‘false catsharks’ are members of thePseudotriakidae), ‘dogfish’ to the Squaliformes, and ‘sandsharks’ in the form of ‘sand t iger shark’ to theOdontaspididae. Orectoloboid ‘catsharks’ are termed‘carpet sharks’, and ‘sand sharks’ and ‘smooth dogfishes’ ofthe triakid genus Mustelus are termed ‘smoothhounds’(except for M. antarcticus, the Australian ‘gummy shark’).

Keys, Field Marks and Diagnostic Features. Thesesections include identification data in different forms. Keys toorders, families, genera and species are standarddichotomous biological keys that are followed in steps ofalternate choices to single out the taxa covered. DiagnosticFeatures are comprehensive lists of characters at theordinal, familial, generic, and species level, with thecharacter choice generally limited to external characters,particularly at the species level, because of spaceconsiderations and their primary purpose of identificationrather than indication of relationships. Some exceptions aretaken with higher taxonomic levels, to support a solid, soundhigher classification. The Diagnostic Features sections arehierarchical, with characters at the ordinal level notduplicated at the family, genus and species levels.Monotypic orders with one fami ly (such asPristiophoriformes), monotypic families with one genus(Chlamydoselachidae) or monotypic genera with onespecies (Carcharodon) all have the Diagnostic Featuressection present only in the highest taxon covered. In amonotypic order, Diagnostic Features are omitted in theaccount of its single family; in a monotypic family, they areomitted from its single genus; and in a monotypic genus,they are omitted from its single species.

Field Marks generally include a few obvious characters ofuse in field identification, extracted from DiagnosticFeatures at various levels, but included in a separatesection. Field Marks are listed at the ordinal, familial andspecies levels, and occasionally the generic level in cases oflarge genera with many species. The arrangement of FieldMark characters is semihierarchical and pragmatic and mayinclude characters from a higher level such as an order inlower level taxonomic accounts such as those of species.


An example of the different application of DiagnosticFeatures and Field Marks is indicated with the sevengillshark, Heptranchias perlo. Starting with the orderHexanchiformes, Diagnostic Features applicable to it aregiven at decreasing hierarchical levels through the familyHexanchidae and genus Heptranchias (a monotypicgenus). However, the species account of H. perlo also has ashort Field Marks section, “A narrow-headed, big-eyed,small seven-gilled shark with one dorsal fin, no dark spots,and a black blotch on the dorsal fin (inconspicuous in largeindividuals)”, that can suffice to identify it without additionalinformation, although this is available in the DiagnosticFeatures sections as needed. In some large families such asthe Carcharhinidae the Field Marks for an easily recognizedspecies such as Carcharhinus longimanus may not repeatfamilial and ordinal characters but merely indicates its familyand unique characters.

Distribution and Maps. Geographic distributions for nearlyall species of sharks are given by listing the countries off thecoasts of which the sharks occur, and, in some instanceswith large countries (Australia) or those with coasts frontingmore than one ocean (e.g. Mexico, South Africa), moredetailed data are given when available. In compilingdistributional data and preparing maps it was noted that thedistributions of many wide-ranging coastal species are veryspottily known as present, especially with species occurringin the Indian and western Pacific Oceans. In many casesgaps in distribution may not indicate absence of a givenspecies but absence of knowledge. Continental slope sharkfaunas are poorly known for much of the world, and anumber of deepwater species probably have wider rangesthan are currently known. A recent example of this is thecapture of the Australian and New Zealand sharksProscymnodon plunketi and Parmaturus macmillani onsubmarine ridges south of Madagascar and east of SouthAfrica by a commercial bottom trawler in 1999. The localitydata in the literature and on specimen labels is often verygeneral and imprecise; and even with bottom or pelagictrawl hauls with detailed oceanographic data and accuratecoordinates, hauls may be of such long duration thatlocations are approximate. Longline locality data can bemore accurate than trawls thanks to GPS or other navigationsystems, but often is not accurate because detail data werenot collected when specimens were landed. Hencedistributional data and maps presented here are to beconsidered as rough approximations of distribution. Some ofthe data comes from a database (approximately 14 000records) of shark distribution compiled by the writer andplotted with commercial digital mapping programmes and aspreadsheet-based programme for southern Africadeveloped by the writer. Much effort was made to screen outerrors of shark distribution, based on misidentifications ofspecies, at a cost of presenting distributional lists and mapsthat are spotty if more accurate. An extreme example isdiscussed in detai l under Glyphis gangeticus(Carcharhinidae; see volume 3).

Elasmobranchs are primarily marine organisms, but anumber of species readily enter brackish to almostfreshwater estuaries, river mouths, lagoons and bays; a fewspecies of the family Carcharhinidae and many batoidsoccur far up rivers and in freshwater lakes with connectionsto the sea. Records of elasmobranchs in fresh water werereviewed by Compagno and Cook (1995), who classifiedspecies as euryhaline (occurring in fresh, brackish and saltwater, and found far from the sea), marginal (peripheralspecies penetrating fresh water in estuaries or the lowerreaches of rivers, but not extending far up river), brackish

(found in water of reduced salinity, but not in fresh or saltwater), and obligate (found in fresh water only, and not in saltwater).

In the case of certain carcharhinid sharks (the bull shark,Carcharhinus leucas and the river sharks, Glyphis spp.)that are known from verifiable records from entirelyfreshwater parts of rivers and freshwater lakes, the names ofmajor river systems and lakes where they occur are noted.There are various freshwater records of other members ofthe family Carcharhinidae and several other families ofnonbatoid sharks (including the zebra shark family,Stegostomatidae), but some of these records may be ofmarginal species from semi-brackish lower reaches of riversand estuaries and may indicate that the species involved aretolerant of reduced salinities but are not truly euryhaline.Some of these carcharhinid freshwater records may bebased on C. leucas or Glyphis species rather than thespecies indicated (such as C. melanopterus or C.hemiodon). Batoids are more numerous than nonbatoidsharks in fresh water, including several sawfish (Pristidae),potamotrygonid stingrays, and several dasyatid stingrays.Many stingrays are obligate freshwater species.

For the compilation of maps of distribution in the presentcatalogue, a new approach has been undertaken to betterrepresent the real distribution of each species. The mainsource of information for building the maps was that given ineach species’ account under Habitat and Distribution. Itwas possible to use this information using a modern GISapproach after standardizing all the terminology provided inthe species accounts following the method briefly explainedbelow.

For those species that show some type of relationship withthe ocean bottom, the depth information given underHabitat has been translated into pre-chosen depth rangesusing the tables shown below. These depth ranges wereextracted from a single data set, i.e. GEBCO Digital Atlas(Natural Environment Research Council. 1994. Digitalversion of the IOC/IHO General Bathymetric Chart of theOceans) and transferred to a GIS. Then, geographicdistribution information on localities and oceanographicprovinces were extracted from WVS (World VectorShoreline, at scale 1:43.000.000) and ArcWorld (distributedby ESRI (Environmental Systems Research Institute), 380New York St., Redlands, California, 92373-8100, USA) andoverlaid with the previous information to produce the finaloutput. With this methodology, the maps for bottom-dwellingor coastal species give a better idea of the spatial coverageof their distribution as inferred from our current knowledge.This can give an approximate idea of the relative size ofdifferent stocks among and between species.

Criteria used to define upper and lower limits of habitatwhen compiling maps of distribution.


Coast-line

Coastalarea

Uppercontinental

shelf

Deepshelf

Upperslope

Maximumlimit of the

slope

0 50 100 200 500 1 000

If specific depth ranges were given under Habitat, suchvalues were used after rounding them according to Table 2below, using the closest values found. In cases of valueslarger than 1 000 m, the 1 000 m isobath was used.

Table 1Lower limits (m) used for different marine habitats

For species with an oceanic habitat, the main source ofinformation was their known geographic distributionirrespective of depth. Thus, the maps of oceanic speciesgive only information on distribution.

All data were transferred to hand drawn maps which weredirectly digitized and georeferenced using WVS andArcWorld for the exact plotting of localities and oceanicprovinces.

Where necessary, maps show two different kinds ofdistribution for a given species. Dark red is used to show theknown and certain distribution of a species from reliablerecords, whilst light red or orange is used to show thesuspected or uncertain distribution of a species.

Maps presented in the Catalogue can be largely divided intotwo categories, Global (or world maps) and Regional maps.For better visualization, global maps include the speciesdistribution and the land masses especially generalized andprepared from the WVS data set. The regional maps, inaddition to the above, include the 200 m depth isobath as areference of their depth distribution.

Note: Whenever the narrowness of the continental or insularshelves and the scale of the maps have caused parts of thedistribution of a species to be undistinguishable, colouredarrows have been used on the map to point to suchdistribution areas.

Habitat. Habitat covers information on physical conditionswhere various sharks are found. The known depth range ofthe species (in metres), position in the water column, type ofsubstrate occupied, and preferences relative to coasts arenoted when available. In most cases data on salinity, oxygencontent, and specific temperature of the water in which theyoccur was not available or was not in an easily usable formand has not been regularly compiled here.

Biology. Includes data on population structure anddynamics, reproduction, behaviour, sociobiology, age andgrowth, and feeding. Compilation of these data suggeststhat very few species of sharks are biologically well known,and even in the piked dogfish (Squalus acanthias), perhapsthe best-known of living cartilaginous fishes, there are areasof its biology that are very poorly known (such as itsbehaviour and sociobiology). There is a bias in availablenatural history data towards reproductive biology, feeding,and fisheries-related subjects such as age and growth, andcorrespondingly l i t t le on ecology, behaviour andsociobiology.

Size. All size data are given as total lengths; this is themeasurement most often used as an independent variableand standard measurement in the shark literature, althoughparticularly in fisheries papers precaudal lengths, forklengths, and other measurements have been used fromchoice or necessity. Unfortunately shark workers have notagreed on a standard method of measuring total length, sototal lengths from different sources in the literature may notbe strictly comparable. I prefer and advocate as a standardmethod a direct measurement, in which the shark is heldbelly down with its dorsal caudal-fin lobe depressed into linewith its body axis and total length measured as a point topoint distance (not over the curve of the body) from the snouttip to the tip of the dorsal caudal-fin lobe (see alsoCompagno, 1988). This method lends itself readily to quickuse of a fishboard with a perpendicular front bar or plate toindex the shark’s snout against, a one metre or two metreruler or folding rule slipped under the shark, or even a steelor cloth tape, and avoids the trouble of computation andpossible errors and loss of data.

A comparable computational method adding the precaudallength and dorsal caudal-fin margin is advocated bySadowsky (1968). Bigelow and Schroeder (1948) andSpringer (1964) measured total length from the snout tipalong the body axis to a vertical projection from the tip of thedorsal caudal-fin lobe with the caudal fin in a ‘naturalposition’. Bass (1973) advocated a computational methodwhich adds the precaudal length to a number computed bymultiplying the length of the dorsal caudal-fin margin by aconstant (1.0 or less, 0.97 and 0.80 were the numbers) thatcorrects for the different ‘natural angles’ of the caudal axis tothe body axis in different species. The method advocated


For original depth data in the interval Limit used

0-30 0

31-75 50

76-150 100

151-250 200

251-751 500

751 and below 1 000

If more than one bathymetric range of distribution wasmentioned (e.g. different ranges for adults and juveniles),the widest range given was used. However, when differentdepth ranges existed for different regions or areas, eachwas chosen and plotted independently.

If no depth data was mentioned in the original account,textual descriptions have been translated using the criteriain Table 3 below.

Table 2Limits used to convert upper and lower limits of

depth ranges (m)

Fot text indicatingUpperlimit

Lowerlimit

Shelf or continental shelf 0 200

Shallow waters, inshore waters, coastal 0 50

Continental shelf, neritic 0 200

Upper shelf 0 100

Deep shelf 100 200

Slope 200 1 000

Upper slope 200 500

Deep slope 500 1 000

Terms like benthic, pelagic, surface, bottom deeper water,deepish, great depths included under Habitat were notused. If more than one type of habitat was given, the onecorresponding to the widest possible range of distributionwas used.

Table 3Upper and lower limits of depth ranges (m) used for

textual descriptions of habitat

here and in Compagno (1984, 1988) dispenses with allcomputation and avoids arbitrary constants to correct forsupposed ‘natural positions’ of the caudal axis as well as thedifficulties in obtaining accurate vertical projections from thecaudal tips held in ‘natural positions’. Also, with the presentmethod a comparable measurement can be obtained for allor most sharks, rays and chimaeras, although there areproblems with species that have greatly elongatedfilamentous snouts or tails. In contrast methods using‘natural positions’ arbitrarily generate incompatible totallengths for different groups of sharks, and also do not takeinto account changes in the angle of the caudal axis whensharks swim or as they grow (Compagno, 1988).

Total length data presented includes maximum size, size atmaturity (in some cases, a size range at maturity, whenabundant data were available) and maximum size for bothsexes (as sexual dimorphism in size is nearly universalamong sharks, with females usually attaining larger sizesthan males, except for some scyliorhinid catsharks wherethe reverse occurs), and size at birth or hatching.Sometimes size at sexual maturity for either or both sexes isnot known, in which cases reported minimum and maximumsizes of adult individuals are given. In some cases maximumsize exceeds that recorded for either sex, in which case thesex of the outsized individual or individuals representing themaximum size measurements was not indicated. In somepoorly known species only immature individuals are known,in which case the hypothetical maximum adult size is almostcertainly larger than the known immature maximum (nocases are known of adult sharks that are considerablysmaller than large immature individuals of the same sex,unlike some other vertebrates). The writer tends to discountold, unverifiable size records of some well-known species,but mentions them as such.

Some fisheries biologists and shark researchers useprecaudal length (PCL) or fork length (FL) as standardlengths instead of total length. The first eliminates problemswith sharks having damaged caudal fins but is difficult todetermine on some sharks with weakly defined uppercaudal-fin origins. The second is only applicable to specieswith notched caudal fins and defined upper and lowerpostcaudal-fin margins.

In some species length-weight equations are presented,usually of the form W = a + TLb, where W is weight, a and bare constants, and TL is total length.

Interest to Fisheries and Human Impact. This section isexpanded in scope from the 1984 catalogue, and in additionto fisheries information includes many other aspects ofhuman interaction with sharks. In this section data onlocalities of fisheries, gear used, and uses of the particularspecies are noted when available. National fisheries data forsharks is often sketchy and combined for a number ofspecies. Thus, catch statistics were available for relativelyfew species of sharks but are noted when available, withparticular emphasis on data from those species reported toFAO. Additional data for sharks are increasingly availablefrom national and regional fisheries bodies, but were used ina very limited way here due to time and literatureconstraints.

Initially data from the hard-copy FAO species yearbookswere used for compil ing shark fisheries data onspreadsheets, as in Compagno (1990c), but this has beengreatly facilitated by the advent of FAO FishStat, a

data-handling and analytical software package which can bedownloaded free from the FAO Fisheries website(http://www.fao.org/fi). FishStat handles a variety ofannually revised FAO fisheries statistics databases and canexport files into other programmes such as spreadsheetsand databases.

Conservation and management issues and importance ofsharks to human recreation including ecotouristic diving andvisits to public aquaria are covered in this section. It alsoincludes aspects of shark behaviour that were formerlyplaced in the biology section, that is, shark encounters withpeople. The 1984 Catalogue used the universal term ‘sharkattack’ for encounters when sharks bite or otherwise injurepeople. I have tried to avoid this term in this Cataloguebecause of its extremely negative, subjective, andmisleading connotations, along with a few other hyperbolicterms such as ‘maneater’. I realize that the general publicand especially the news and entertainment media willcontinue to use these emotive terms for a long time despitethe limited realities. It is challenging to think of ways ofdiscussing the subject without the dreadful, gory ‘sharkattack’ image being brought forth, but it does help to buildalternate and more realistic images of a minuscule objectivephenomenon. This is discussed in more detail under SharkEncounters in the third volume of the Catalogue.

Local Names. A change from the 1984 Catalogue is thatlocal or regional family and species names in variouslanguages are generally listed when available under aseparate local names heading. These were compiled fromthe same sources used for FAO names (see above), butwhat is presented here is not comprehensive andrepresents what was readily available to the writer. Manyspecies have no vernacular names whatsoever or arelumped under catchall names, while some sharks such asthe white and basking sharks have dozens of names.Obviously some sharks have more of an impact or are muchmore familiar than others, and these get more names (someof which seem like curses or jokes). Wherever possible localnames are presented for important wide-ranging sharks,including fisheries species such as Galeorhinus galeus(‘school shark’ in Australia, ‘tiburón vitaminico’ or ‘vitaminshark’ in Uruguay and Argentina, ‘soupfin’ or ‘oil shark’ offthe Pacific USA and Canada, and ‘vaalhai’ in South Africa)and Carcharias taurus, the very popular shark for fisheries,public aquaria, ecotourism, and conservation (termed‘ragged-tooth shark’ in South Africa, ‘grey nurse shark’ inAustralia, ‘requin sable’ in West Africa, and ‘sand tiger shark’or ‘sand shark’ off the east coast of the United States). Thebroadening interest in sharks and urgent need to acquirespecies-specif ic data for their management andconservation should encourage fisheries biologists andother researchers to compile local names for their owncountries or regions, and add to our sketchy knowledge oflocal names worldwide.

Remarks. Important information, especially on systematicsand nomenclature are given in the remarks section.

Literature. References cited here include specific workswith important information for each species and family aswell as comprehensive accounts, but are not intended as acomprehensive bibliography. Reference sections have beenupdated and given more extensive coverage than the 1984Catalogue.



1.2 Technical Terms and Measurements

1.2.1 Picture Guide to External Terminology of Sharks

Fig. 2 Lateral view

nostril second dorsal fin

anal fin

clasper (males)

mouth

snout

eye

dorsal-finspine

first dorsal fin

labialfurrows

gillopenings

pectoral fin

pelvic fin

caudalkeel

caudal fin

precaudal pitspiracle

head trunk tail

Fig. 3 Ventral view

mouth

pectoral fin

caudal finanal fin

preanal ridges

precaudal tail

pelvic fin(female, no claspers)

snout

nostril

gill slits

trunk

vent

Fig. 4 Head of an orectoloboid shark(ventral view)

anterior nasal flap lifted

nasoral groove

mouth

symphisial groove

anterior nasal flap

lower labial furrow

barbel

circumnarial groove

incurrentaperture

circumnarial fold

upper labial furrow

excurrent aperture

Fig. 5 Nostril

excurrent aperture

posteriornasal flap

anteriornasal flap

incurrent aperture


Fig. 6 Eyes

upper eyelid

nictitatinglower eyelid

notch

secondarylower eyelid subocular pocket

Fig. 7 Mouth corner

labial fold

labial furrow

Fig. 8 Dorsal fin

origin

base

insertion

inner margin

posteriormargin

apex

spine

anteriormargin

freereartip

Fig. 9 Caudal fin

lower origin

ventral tipventral lobe

preventral margin

upper origin

posterior tipterminal lobe

lower postventral margin

posterior notch

epaxial web

dorsal lobe

dorsal margin

subterminal margin

subterminal notch

upper postventral margin

terminal margin

hypaxial web

Fig. 10 Pectoral fin

inner margin

free rear tip

posteriormargin

anteriormargin

fin origin

base

fin insertion

apex Fig. 11 Dorsal view of clasper(lamnid shark)

ANTERIOR �

� MEDIAL LATERAL �

pelvic fin

coverrhipidion

clasperspur

POSTERIOR �

hypopyle

clasper tip

rhipidion

apopyle

claspergroove

lateralfold

claspershaft

clasper glans

pseudosiphon

1.2.2 Picture Guide to Skeletal Terminology of Sharks


rostrum

nasal capsule

internasal plate

preorbital process

anterior fontanelle

cranial roof

parietal fossa

foramen magnum

hyomandibular facet

otic capsule

stapedialfenestra

basal plate

suborbital shelf

orbital notch

subethmoidfossa

nasal aperturenasal fontanele

supraorbital crest

postorbital process carotid

foramen

occipital centrumPOSTERIOR �

b) VENTRAL VIEWa) DORSAL VIEW

ANTERIOR �

Fig. 12 Chondrocranium

optic nerve foramen

suborbital shelf

hyomandibular facet

sphenopterotic ridge

otic capsule

supraorbital crest

nasalcapsulerostrum orbit

cranial roof

pterotic horn

stapedial fenestranasal aperture

orbital notch

rostralnode

� ANTERIOR POSTERIOR �

c) LATERAL VIEW

Fig. 13 Aplesodic and plesodic pectoral fins

propterygium

radials

metapterygium

distalradials

intermediate radials

basals

basals

mesopterygium

metapterygium

proximal radials

metapterygial axis

intermediate radials

distalradial

radials

a) APLESODIC b) PLESODIC

metapterygial axis

propterygium


Fig. 14 Clasper skeleton of lamnid shark (right side)

basipterygium

axialcartilage

apopyle

dorsalmargina

l

claspergroove

intermediate segments

betacartilage

hypopyle

dorsalterminal

dorsalterminal 2

erect

folded

terminal 3cartilage

ventraltermnal

end-style ofaxial cartilage

MEDIAL

LATERAL

ventralmarginal

a) DORSAL

axial cartilage

appendix-stemof axial

dorsalterminal

dorsalmarginal

ventralmarginal

b) VENTRAL

ventralterminal

LATERAL MEDIAL

c) DORSAL (TERMINAL 3 CARTILAGE ANDDORSAL TERMINAL 2 REMOVED)

ventralmarginal

ventralterminal

end-styleof axial

cartilage

dorsaltermina

LATERAL

MEDIAL

dorsalmarginal

Fig. 15 Tooth terminology (left upper anterolateral tooth)a) LABIAL VIEW b) LINGUAL VIEW

�APICAL

root

crownfoot

cusp

root

crown cusp

crown foot

transverse groove

root

central foramencusplet

transverseridges

MESIAL � � DISTAL �

BASAL�

transverse notch

� MESIAL

mesial rootlobe

distal rootlobe

cutting edgeserrations

root

crown

basalledge

cusplet

blade

neck

basal groove

cusplet

Fig. 16 Oblique anterolateral view of lateral trunk dermal denticle

ANTERIOR

POSTERIOR

medial cusp

medial ridge

base

pedicel

crown

lateral ridgelateral cusp

1.2.3 Measurements Used for Sharks

TL = TOTAL LENGTH PP2 = PREPELVIC-FIN LENGTHFL = FORK LENGTH SVL = SNOUT-VENT LENGTHPCL = PRECAUDAL-FIN LENGTH PAL = PREANAL-FIN LENGTHPD2 = PRE-SECOND DORSAL-FIN LENGTH IDS = INTERDORSAL SPACEPD1 = PRE-FIRST DORSAL-FIN LENGTH DCS = DORSAL CAUDAL-FIN SPACEHDL = HEAD LENGTH PPS = PECTORAL-FIN PELVIC-FIN SPACEPG1 = PREBRANCHIAL LENGTH PAS = PELVIC-FIN ANAL-FIN SPACEPSP = PRESPIRACULAR LENGTH ACS = ANAL-FIN CAUDAL-FIN SPACEPOB = PREORBITAL LENGTH PCA = PELVIC-FIN CAUDAL-FIN SPACEPP1 = PREPECTORAL-FIN LENGTH VCL = VENT CAUDAL-FIN LENGTH

PRN = PRENARIAL LENGTHPOR = PREORAL LENGTHEYL = EYE LENGTHEYH = EYE HEIGHTING = INTERGILL LENGTHGS1 = FIRST GILL SLIT HEIGHTGS2 = SECOND GILL SLIT HEIGHTGS3 = THIRD GILL SLIT HEIGHTGS4 = FOURTH GILL SLIT HEIGHTGS5 = FIFTH GILL SLIT HEIGHTGS6 = SIXTH GILL SLIT HEIGHTGS7 = SEVENTH GILL SLIT HEIGHTP1A = PECTORAL-FIN ANTERIOR MARGINP1R = PECTORAL-FIN RADIAL LENGTHP1B = PECTORAL-FIN BASEP1I = PECTORAL-FIN INNER MARGINP1P = PECTORAL-FIN POSTERIOR MARGINP1H = PECTORAL-FIN HEIGHTP1L = PECTORAL-FIN LENGTHSOD = SUBOCULAR POCKET DEPTH


Fig. 17 Main longitudinal measures

TL

FL

PCL

PAL

PD2

PD1

HDL

PG1

POB

IDS

PP1 PPS

SVL

DCS

PAS

PCA

ACS

VCL

PSP

PP2

Fig. 18

POR

PRN

EYL

EY

H

GS

1

ING

GS

5

P1I

P1

H

P1

PP1A

P1L

SO

D

P1R

CDM = DORSAL CAUDAL-FIN MARGINCPV = PREVENTRAL CAUDAL-FIN MARGINCPU = UPPER POSTVENTRAL CAUDAL-FIN MARGINCPL = LOWER POSTVENTRAL CAUDAL-FIN MARGINCFW = CAUDAL-FIN FORK WIDTHCFL = CAUDAL-FIN FORK LENGTHCST = SUBTERMINAL CAUDAL-FIN MARGINCSW = SUBTERMINAL CAUDAL-FIN WIDTHCTR = TERMINAL CAUDAL-FIN MARGINCTL = TERMINAL CAUDAL-FIN LOBE

D1L = FIRST DORSAL-FIN LENGTHD1A = FIRST DORSAL-FIN ANTERIOR MARGIND1B = FIRST DORSAL-FIN BASED1H = FIRST DORSAL-FIN HEIGHTD1I = FIRST DORSAL-FIN INNER MARGIND1P = FIRST DORSAL-FIN POSTERIOR MARGIN

D2L = SECOND DORSAL-FIN LENGTHD2A = SECOND DORSAL-FIN ANTERIOR MARGIND2B = SECOND DORSAL-FIN BASED2H = SECOND DORSAL-FIN HEIGHTD2I = SECOND DORSAL-FIN INNER MARGIND2P = SECOND DORSAL-FIN POSTERIOR MARGIN

P2L = PELVIC-FIN LENGTHP2A = PELVIC-FIN ANTERIOR MARGINP2B = PELVIC-FIN BASEP2H = PELVIC-FIN HEIGHTP2I = PELVIC-FIN INNER MARGIN [LENGTH]P2P = PELVIC-FIN POSTERIOR MARGIN [LENGTH]

ANL = ANAL-FIN LENGTHANA = ANAL-FIN ANTERIOR MARGINANB = ANAL-FIN BASEANH = ANAL-FIN HEIGHTANI = ANAL-FIN INNER MARGINANP = ANAL-FIN POSTERIOR MARGIN

HDH = HEAD HEIGHTTRH = TRUNK HEIGHTABH = ABDOMEN HEIGHTTAH = TAIL HEIGHTCPH = CAUDAL-FIN PEDUNCLE HEIGHTDAI = SECOND DORSAL-FIN INSERTION ANAL-FIN

INSERTIONDAO = SECOND DORSAL-FIN ORIGIN ANAL-FIN ORIGIN

DPI = FIRST DORSAL-FIN MIDPOINT PECTORAL-FININSERTION

DPO = FIRST DORSAL-FIN MIDPOINT PELVIC-FIN ORIGINPDI = PELVIC-FIN MIDPOINT FIRST DORSAL-FIN

INSERTIONPDO = PELVIC-FIN MIDPOINT SECOND DORSAL-FIN

ORIGIN


Fig. 19 Measurements of caudal fin

CDM

CPU CST

CS

W

CTR

CTL

CF

W

CFL

CPL

CPV

Fig. 20 Measurements of dorsal, pelvic and anal fins

D1A

D1

H

D1P

D1ID1B

D1L

D2LD2B

D2I

D2H

D2A D2P

P2L

P2B P2IANB

ANLANI

AN

P

AN

H

ANAP2P

P2

H

P2A

Fig. 21 Other common measurements

DPI DPODAO DAI

CP

H

PDOPDI

HD

H

TR

H

AB

H

TA

H


MOL = MOUTH LENGTHMOW = MOUTH WIDTHULA = UPPER LABIAL-FURROW LENGTHLLA = LOWER LABIAL-FURROW LENGTHNOW = NOSTRIL WIDTHINW = INTERNARIAL SPACEANF = ANTERIOR NASAL-FLAP LENGTH

CLO = CLASPER OUTER LENGTHCLI = CLASPER INNER LENGTHCLB = CLASPER BASE WIDTH

INO = INTERORBITAL SPACESPL = SPIRACLE LENGTHESL = EYE SPIRACLE SPACEHDW = HEAD WIDTHTRW = TRUNK WIDTHABW = ABDOMEN WIDTHTAW = TAIL WIDTHCPW = CAUDAL-FIN PEDUNCLE WIDTH

Fig. 22

GIR

NO

W

ANF

a) NOSTRIL

CLO

CLI

CL

B

b) CLASPER

GIR = GIRTH

INW MOL

MO

W

LLA

ULA

d) ANGLE OF MOUTH

SPL

c) VENTRAL VIEW

ESL

INO

HD

W

TR

W

AB

W

TA

W

CP

W

f) DORSAL VIEW

e) DORSO-LATERAL VIEW


Fig

.23

Hig

her

clas

sifi

cati

onof

shar

ks(O

rder

s)

1.2.4 Glossary of Technical Terms

The following glossary of terms used for the anatomy andbiology of shark-like fishes is modified from terms inCompagno (1984, 1988, 1999) and a short glossary inCompagno, Ebert and Smale (1989).

Abdominal ridges or keels: In some sharks, pairedlongitudinal dermal ridges that extend from the bases of thepectoral fins to the pelvic-fin bases.

Accessory dorsal marginal: In the clasper skeleton, a flatcartilage on the posterior end of the dorsal marginalcartilage that supports the cover rhipidion.

Adductor mandibulae muscles: Paired head musclesoriginating on the lateral faces of the quadrate process ofthe palatoquadrates and inserting on the lateral surface ofthe Meckel’s cartilages; the primary jaw-closing muscles ofsharks.

Adelphophagy: Foetus-eating, a mode of live-bearingreproduction employing uterine cannibalism; early foetusesdeplete their yolk-sacks early and subsist by first eating theirsmaller siblings and then eating nutritive eggs produced bythe mother. At present only known for certain in the sandtiger shark (Carcharias taurus), but suspected in a fewother lamnoids.

Alternate teeth: Small oral teeth with asymmetrical crownsthat form two interdigitated rows on the symphysis, with thecusps of each row hooked mesially towards the oppositerow. Additional paired rows of alternates may be presentdistal to the symphysial rows.

Amphitemperate: Referring to a species that occurs intemperate water in the northern and southern hemispheres,but is absent from the tropics.

Anal fin: A single fin on the ventral surface of the tailbetween the pelvic fins and caudal fin of some sharks,absent in batoids, dogfish, sawsharks, angel sharks, andsome chimaeras.

Annular rings or annuli: In a vertebral centrum in crosssection, rings of calcified cartilage separated by uncalcifiedcartilage that occupy the intermedialia only, or concentricrings that cross both the intermedialia and basalia.

Anterior: Forward, in the longitudinal direction of the snouttip. Also, cranial.

Anterior fontanelle: On the elasmobranch neurocranium,an aperture on the anterodorsomedial surface, usually atthe rear of the ethmoid region and forming a passage intothe internal cranial cavity. It is closed by a tough membrane,varies tremendously in shape, and may be pinched off bythe medially expanded orbits in a few sharks.

Anterior margin: In precaudal fins, the margin from the finorigin to its apex.

Anterior nasal flap: A flap on the front edges of the nostrils,that serves to partially divide the nostril into incurrent andexcurrent apertures or openings.

Anterior teeth: Enlarged, tall, narrow-rooted oral teeth nearthe symphysis, often with lingually curved cusps.

Anterodorsal palpebral depressor muscle: In theorectoloboid family Parascylliidae, paired head muscles thatoriginate at the insertions of the preorbitalis muscles on theanterolateroventral face of the Meckel’s cartilage, and inserton the skin of the upper eyelid anterior to the eye. These arepossibly for depressing the upper eyelids and closing theeyes, and are not found in any other sharks.

Antorbital cartilages: On the neurocranium of sawsharksand batoids, separate cartilages attached to the sides of thenasal capsules that support the sides or front of the head.

Apex: In precaudal fins, the distal tip, which can be acutelypointed to broadly rounded.

Apical: In oral teeth, towards the tip of the crown or cusp.Can also be used as indicating direction towards the apex ortip of a fin, fin-spine, etc.

Aplacental viviparity: Live-bearing in which the young donot have a yolk-sac placenta. Found in all groups oflive-bearing sharks.

Aplesodic fin: A pectoral, pelvic, dorsal, or anal fin in whichthe fin radial cartilages do not extend into the distal fin weband between the supporting ceratotrichia of the fin web.Modern sharks always have aplesodic caudal fins, in whichthe haemal arches of the caudal vertebrae do not supportthe ventral caudal lobe.

Apopyle: The anterior opening of the clasper, on theanteromesial surface of the clasper and close to the vent.The apopyle receives sperm from the cloaca and fluid fromthe siphons, which enter the clasper groove and aredischarged through the hypopyle. Apopyle is also used forclasper skeletons for the anterior opening of the tubularshafts formed by enlarged marginal and axial cartilages.

Axial cartilage: In the clasper skeleton, the elongatedventral rod or plate-shaped cartilage that forms the mainsupport of the clasper. Also termed appendix-stem.

Barbels: Long conical paired dermal lobes on the snouts ofsharks, that may serve to locate prey. Sawsharks havebarbels on the underside of the snout in front of the nostrilsas in sturgeon, but most barbelled sharks have themassociated with the nostrils, either as an extension of theanterior nasal flaps or as separate structures medial to thenasal apertures.

Basal: In oral teeth, a proximal direction towards the crownfoot and roots.

Basal cartilages or basals: In precaudal fins the largecartilages of the fin bases, immediately distal to the pectoraland pelvic fin girdles or the vertebral column (dorsal andanal fins), on which the radials articulate distally. The pairedpectoral fins of living sharks primitively have a tribasalpectoral fin, with a propterygium, mesopterygium, andmetapterygium as basals, although these may be fused; inbatoids, additional neopterygial basals may be addedbetween the mesopterygium and metapterygium and thepropterygium is variably expanded anterior with apropterygial basal and axis. The pelvic fins have abasipterygium that supports the pelvic radials and, in males,the claspers. The caudal fin has no basals, but these are



functionally replaced by expanded neural and haemalarches of the vertebral column.

Basal communicating canals: See subnasal fenestrae.

Basal groove: In oral teeth, a deep groove proximal to thebasal ledge on the labial surface of the crown neck andapical root margin.

Basal ledge: In oral teeth, a shelf-like projection on thelabial surface of the crown foot.

Basal plate: The floor of the cranial cavity of theneurocranium, a ventral, medial plate extending from theethmoid region between the orbits and otic capsules andbelow the cranial cavity to the occipital condyles, occipitalcentrum and foramen magnum.

Basals or basalia: In a vertebral centrum, the diagonalspaces below the attachment surfaces of the basidorsalcartilages, above the basiventral cartilages, and betweenthe two halves of the double cone. Basalia may be filled withuncalcified cartilage, may have diagonal calcificationspenetrating the uncalcified cartilage, or may have calcifiedannuli or solid calcified cartilage that are continuous withcalcification of the intermedialia. See diagonal calcificationsand intermedialia.

Base: In precaudal fins, the proximal part of the fin betweenthe origin and insertion, extending distally, and supported bythe cartilaginous fin skeleton. In the caudal fin, thatthickened longitudinal part of the fin enclosing the vertebralcolumn and between the epaxial and hypaxial lobes or websof the fin. In oral teeth, the proximal root and crown foot, inapposition to the distal cusp. In denticles, the proximalanchoring structures, often with four or more lobes, holdingthe denticles in the skin.

Basidorsal cartilages: A pair of wedge-shaped arched, thincartilages articulating with the dorsolateral surfaces of avertebral centrum and forming a continuous neural arch withthe interdorsal cartilages to protect the spinal cord.

Basipterygium: The large elongate longitudinal cartilage atthe fin base of the pelvic fin, attached to the posterolateralends of the pelvic girdle or puboischiadic bar. Thebasipterygium has pelvic radials attached along its distaledge and has the clasper skeleton attached posteriorly inmales.

Basiventral cartilages: A pair of rounded or wedge-shapedcartilages on the ventrolateral surfaces of a vertebralcentrum that form the bases for attachment of ribs inmonospondylous precaudal vertebrae. In diplospondylousprecaudal and caudal vertebrae the basiventrals formhaemal arches along with the interventral cartilages forprotecting the caudal artery and vein.

Batoid: A ray or flat or winged shark, a neoselachian of thesuperorder Squalomorphii, order Rajiformes: a sawfish,sharkray, wedgefish, guitarfish, thornray, panray, electricray, skate, stingray, butterfly ray, eagle ray, cownose ray,devil ray or manta. Rays are closely allied to the sawsharks(Pristiophoriformes) and angel sharks (Squatiniformes), butdiffer from them in having the pectoral fins fused to the sidesof the head over the gill openings, which are ventral ratherthan laterally or ventrolaterally placed.

Beta cartilage: In the clasper skeleton, a single,dorsolateral flattened, wedge-shaped or cylindrical cartilage

connecting the pelvic basipterygium and axial cartilage andreinforcing the intermediate segments, possibly derivedfrom a pelvic radial.

Blade: In oral teeth, an arcuate, convex-edged section ofthe cutting edge of the crown foot, without cusplets.

Body ridges: Elongated longitudinal dermal ridges on thesides of the trunk and precaudal tail in certain carpet sharks(Orectolobiformes), in the whale, zebra and some bamboosharks.

Body: Can refer to an entire shark, sometimes restricted tothe trunk and precaudal tail.

Branchial arches: The paired visceral arches behind thehyoid arch and just in front of the scapulocoracoid thatsupport the gills. In elasmobranchs the five to sevenbranchial arches primitively consist of a pair of dorsomedialand wedge-shaped cartilages, the pharyngobranchials,closely situated against the roof of the pharynx, a pair ofdorsolateral and more cylindrical epibranchials that areconnected dorsomedially to the pharyngobranchials, a pairof ventrolateral cylindrical ceratobranchials that areconnected ventrolaterally to the epibranchials, a pair ofventromedial hypobranchials that are connectedventrolaterally to the ceratobranchials, and unpairedventromedial basibranchials that are connectedventrolaterally to the hypobranchials. The hypobranchialsand basibranchials along with the expanded ventral ends ofthe ceratobranchials form the basibranchial skeleton ofthe floor of the branchial pharynx. The branchial skeleton isvariably modified in elasmobranchs, with basibranchials andsometimes hypobranchials often lost, the last twopharyngobranchials and the last epibranchial often fusedtogether, and the last basibranchial often expanded into along, broad copula with which the anterior hypobranchialsand posterior ceratobranchials articulate.

Calcified cartilage: Shark skeletons are formed of hyalinecartilage or gristle, but this is often reinforced with layers ofcalcified cartilage, cartilage impregnated with a mineral,hydroxyapatite, similar to that of bone but organizeddifferently, in a hard, tile-like pavement of tiny tesserae, ormore compactly as in the calcified structures of vertebralcentra.

Calcified double cones: In vertebrae, the primarycalcifications of the notochordal sheath, in lateral viewresembling two hollow, horizontal cones with their apicesmerged, or an hourglass.

Cannibal viviparity: See uterine cannibalism.

Carcharhinoid: A ground shark, a member of the orderCarcharhiniformes, and including the catsharks, falsecatsharks, finbacked catsharks, barbeled houndsharks,houndsharks, weasel sharks, requiem sharks andhammerheads.

Carina: On the crowns of oral teeth, a low blunt mesodistalridge replacing the cusp and cutting edge, in sharks that eathard-shelled invertebrate prey.

Carotid foramen: A single foramen or one of a pair offoramina that penetrate the basal plate usually near itsmidlength and allow passage of the internal carotid arteriesinto the cranial cavity. In some advanced elasmobranchs thecarotid foramina shift through the stapedial foramina andonto the medial wall of the orbit.


Carti laginous fishes: Members of the classChondrichthyes.

Caudal crest: A prominent saw-like row of enlarged pointeddenticles along the dorsal caudal margin and sometimesalong the ventral caudal margin of the caudal fin. Found incertain sharks including hexanchoids and somecarcharhinoids.

Caudal fin: The fin on the end of the tail in shark-like fishes,lost in some batoids.

Caudal keels: A dermal keel on each side of the caudalpeduncle that may extend onto the base of the caudal fin,and may, in a few sharks, extend forward as a body keel tothe side of the trunk.

Caudal peduncle: That part of the precaudal tail extendingfrom the insertions of the dorsal and anal fins to the front ofthe caudal fin.

Central foramen: In oral teeth, a nutrient foramen on themidline of the lingual surface of the root, in the transversegroove.

Centrum (plural, Centra): A spool-shaped, partially orusually fully calcified structure that forms as a segmentalconstriction in the notochordal sheath of neoselachians, andwhich as an articulated string forms the principal structuralunits of the vertebral column. Centra are primarily formed bythe calcified double cones in the notochordal sheath, whichmay be their only calcification, but additional secondarycalcification may occur in the centrum between the outersurfaces of the calcified double cones, including calcifiedintermedialia, radii, annuli, and diagonal calcifications.

Ceratotrichia: Slender soft or stiff filaments of an elasticprotein, superficially resembling keratin or horn, from theGreek keratos, horn, and trichos, hair. Ceratotrichia run inparallel and radial to the fin base and support the fin webs.The prime ingredient of shark-fin soup.

Chimaera: A member of the order Chimaeriformes,subclass Holocephali, see also Chimaeroid, Holocephali.

Chimaeroid: A chimaera, ratfish, silver shark, ghost shark,spookfish or elephant fish, a member of the orderChimaeriformes.

Chondrichthyan: Referring to the class Chondrichthyes.

Chondrichthyes: The class Chondrichthyes, from Greekchondros, cartilage, and ichthos, fish, a major taxonomicgroup of aquatic, gill-breathing, jawed, finned vertebrateswith primarily cartilaginous skeletons, 1 to 7 external gillopenings, oral teeth in transverse rows on their jaws, andmostly small, tooth-like scales or dermal denticles.Chondrichthyes include the living elasmobranchs andholocephalans and their numerous fossil relatives, and alsocan be termed shark-like fishes or simply sharks.

Chondrocranium: See neurocranium.

Circumnarial fold: A raised semicircular, lateral flap of skinaround the incurrent aperture of a nostril, in heterodontoids,orectoloboids, and a few batoids, defined by a circumnarialgroove.

Circumnarial groove: A shallow groove defining the lateralbases of the circumnarial folds.

Clasper claws: In parascylliid orectoloboids, a longitudinalrow of large anterolaterally directed claw-like denticles onthe dorsolateral surface of the clasper glans, supported bythe terminal ventral.

Clasper dactyl: In parascylliid orectoloboids, a largefinger-like process on the medial face of the clasper,supported by the dorsal terminal and having a mesospur,an analogue to the lateral spur or spine of the terminal 3cartilage of other orectoloboids and other sharks.

Clasper gaff or hook: In the external clasper glans, aposterior hook-like structure, like a clasper spur but formedfrom the dorsal terminal cartilage, found in squaloids of thefamily Squalidae.

Clasper glans: The distal and dorsal part of the externalclasper from the hypopyle to its tip, and including variousmovable terminal structures; also, the same area of theclasper skeleton.

Clasper groove: The longitudinal groove through theclasper, surrounded by the axial and marginal cartilages,and connecting the apopyle and hypopyle.

Clasper hooks: In the clasper glans of some carcharhinoidsharks, small claw-like dermal denticles arranged in a rowalong the ventral surface of the free edge of theexorhipidion.

Clasper sacs: Dermal sacs with longitudinally ribbed wallson the ventral and medial surfaces of the claspers ofhexanchoids.

Clasper shaft: That part of the clasper skeleton from itsorigin on the pelvic fin basipterygium to the hypopyle; also,that part of the external clasper from its base to thehypopyle.

Clasper spine: In the external clasper, a projection of theterminal 3 cartilage on the lateral surface of the clasperglans, which forms a short to long, acutely pointed, spinethat is covered with shiny hard tissue, possibly enameloid,dentine or both. In some squaloids other terminal cartilagesmay have spines.

Clasper spur: In the external clasper, a projection of theterminal 3 cartilage on the lateral surface of the clasperglans, which may be pointed but is not covered with shinyhard tissue.

Clasper tip: The posterior end of a clasper.

Claspers: The paired copulatory organs present on thepelvic fins of male cartilaginous fishes, for internalfertilization of eggs, also termed mixopterygia.

Classification: The ordering of organisms into groups onthe basis of their relationships, which may be by similarity orcommon ancestry.

Cloaca: The common chamber at the rear of the body cavityof elasmobranchs through which body wastes andreproductive products including sperm, eggs, and youngpass, to be expelled to the outside through a commonopening or vent.

Cover rhipidion: On the external clasper glans, anelongated, longitudinal blade or flap on its dorsomedial

external edge, often supported by an accessory dorsalmarginal cartilage.

Cranial cavity: The central cavity of the neurocranium,containing the brain, pituitary gland, and roots of the cranialnerves. It extends posteriorly between the orbits and oticcapsules to the foramen magnum.

Cranial roof: The anterior roof of the cranial cavity of theneurocranium, a dorsomedial, arched or flattened plateextending from the anterior fontanelle and between theorbits to the parietal fossa of the otic capsule. Sometimesperforated by a frontal or parietal foramen or fenestra, whichmay be continuous with the anterior fontanelle and canoccupy most of the cranial roof.

Craniomandibular muscles: Paired head muscles inheterodontoid sharks that originate from long tendons on themedial walls of the orbits that extend below and transverseto the levator palatoquadrati and spiracular constrictormuscles and behind the spiracles to insert on theposterodorsolateral face of the Meckel’s cartilages. Theyare found in no other sharks and may serve to retract orelevate the jaws.

Crown: The distal part of the oral tooth, almost entirelycovered with shiny enameloid except for the neck. Indenticles, a flat dorsal plate-like or thorn-like structure,elevated above the denticle base on a stalk or pedicle orconfluent with the base.

Crown foot: The expanded, proximal, basal part of thecrown, often bearing cusplets or blades.

Cusp: A usually pointed large distal projection of the crown.A primary cusp is situated on the midline of the crown foot.Multicuspid refers to oral teeth or denticles with more thanone cusp. In lateral trunk denticles, the posterior ends of thecrown may have medial and lateral cusps, sharp or bluntprojections associated with the medial and lateral ridges.

Cusplet: As with a cusp, but a small projection inassociation with a cusp, and usually mesial and distal butnot medial on the crown foot.

Cutting edge: In oral teeth, the compressed sharplongitudinal ridge on the mesodistal edges of the crown.

Dentine: The primary material of shark oral teeth, a hardtissue with numerous vascular and nonvascular canals.

Dermal denticle or placoid scale: A small tooth-like scalefound in cartilaginous fishes, covered with enameloid, with acore and base of dentine and usually small and oftenclose-set to one another and covering the body. A fewnonbatoid sharks, many batoids, and chimaeroids generallyhave them enlarged and sparse or reduced in numbers.

Dermal lobes: In wobbegongs, family Orectolobidae,narrow or broad-based, simple or branched projections ofskin along the horizontal head rim and on the chin.

Diagonal calcifications: In a vertebral centrum incross-section, plate-like (diagonal calcified lamellae) orknob-like (diagonal calcified lobes) structures of calcifiedcartilage that partially fills the uncalcified basalia. Thesehave a radial orientation from the centre of the centrum.

Diphycercal: A caudal fin with the vertebral axis runninghorizontally into the fin base, which is not elevated.

Diplospondylous vertebrae: Vertebrae of the tail with twocentra and two basidorsal and basiventral elements persegment, and mostly with a haemal arch formed by thebasiventral and interventral elements. These includediplospondylous precaudal vertebrae between themonospondylous vertebrae and the base of the caudal fin,and diplospondylous caudal vertebrae in the caudal fin.

Distal: In any direction, at the far end of a structure. In oralteeth, used in a special sense for structures on the teethtowards the posterolateral mouth corners or rictuses. Seeapical and basal.

Dorsal: Upwards, in the vertical direction of the back. Seeventral.

Dorsal fin: A fin located on the trunk or precaudal tail orboth, and between the head and caudal fin. Most sharkshave two dorsal fins, some batoids one or none.

Dorsal fin spine: A small to large enameloid-covered,dentine-cored spine located on the anterior margins of oneor both of the dorsal fins, found on bullhead sharks(Heterodontiformes), many dogfish sharks, fossil (but notliving) batoids, chimaeroids, but lost entirely or buried in thefin bases of other shark-like fishes.

Dorsal lobe: In the caudal fin, the entire fin including itsbase, epaxial and hypaxial webs but excepting the ventrallobe.

Dorsal margin: In the caudal fin, the margin from the upperorigin to its posterior tip. Usually continuous, but in angelsharks (Squatiniformes) with their hypocercal, superficiallyinverted caudal fins, it is subdivided. See squatinoidcaudal fin.

Dorsal marginal: In the clasper skeleton, a flatsemicylindrical cartilage that is partially fused to the medialedge of the axial cartilage, and forms the medial wall of theclasper groove.

Dorsal terminal: On the skeleton of the clasper glans, anoften triangular, elongated, curved, plate-like cartilage thatarticulates or is attached to the medial or dorsomedial edgeof the end-style and anteriorly to the dorsal marginal.

Dorsal terminal 2: A flat elongated cartilage with its mesialedge attached to the floor of the glans, and supporting therhipidion.

Ectethmoid chambers: On the neurocranium, cavities inthe nasal capsule that drain the nasal sinuses through theorbitonasal canals into the orbital sinuses.

Ectethmoid processes: On the neurocranium ofhexanchoid and some squaloid sharks, posteroventrolateralangular or lobular projections of the nasal capsules and thepreorbital walls.

Egg case: A stiff-walled elongate-oval, rounded rectangular,conical, or dart-shaped capsule that surrounds the eggs ofoviparous sharks, and is deposited by the female shark onthe substrate. It is analogous to the shell of a bird’s egg andis made of protein, which is a type of collagen thatsuperficially resembles horn or keratin. Egg cases often



have pairs of tendrils or horn-like structures on their ends, orflat flanges on their sides or spiral flanges around theirlengths, which anchor the cases to the bottom. As the eggtravels from the ovaries into the oviducts and through thenidamental glands, the egg case is secreted around it andthe egg is fertilized. Live-bearing sharks may retain eggcases, and these vary from being rigid and similar to those ofoviparous sharks to soft, bag-like, degenerate andmembranous. Soft egg cases may disintegrate during thebirth cycle.

Elasmobranch: Referring to the subclass Elasmobranchii.

Elasmobranchii: The subclass Elasmobranchii, (fromGreek elasmos, plate, and branchos, gills, in allusion to theirplate-like gill septa), the shark-like fishes other than theHolocephali or chimaeras, and including the living nonbatoidsharks, batoids, and a host of fossil species. They differ fromholocephalans in having 5 to 7 pairs of gill openings open tothe exterior and not covered by a soft gill cover, oral teethseparate and not formed as tooth plates, a fixed first dorsalfin with or without a fin spine, and a short spined or spinelesssecond dorsal.

Embryo: An earlier development stage of the young of alive-bearing shark, ranging from nearly microscopic tomoderate-sized but not like a miniature adult. See foetus.

Enameloid: The shiny hard external coating of the crownsof shark oral teeth, superficially similar to enamel in landvertebrates.

End-style: In the clasper skeleton, the posterior end of theaxial cartilage, between the dorsal and ventral terminalcartilages.

Endemic: A species or higher taxonomic group oforganisms that is only found in a given area. It can includenational endemics found in a river system or along part or allof the coast of a given country, but also regional endemics,found off or in adjacent countries with similar habitat, but notelsewhere.

Epaxial lobe or web: In the caudal fin, that part of thecaudal fin between the base and dorsal margin, supportedby ceratotrichia.

Epaxial web: The entire fin web above the vertebral columnand caudal base.

Epiphysial foramen or notch: On the neurocranium, aforamen or notch in the cranial roof at the dorsomedial edgeof the anterior fontanelle, that houses the pineal body.

Ethmoid region: That anteriormost sector of theneurocranium including the nasal capsules, internasal platebetween them, and the rostrum.

Ethmonuchal muscles: In the orectoloboid familyParascylliidae, paired head muscles that originate on thedorsal myomeres of the nape, and insert via long tendons onthe nasal capsules. These are possibly for elevating thesnout. Not found in any other sharks, though analogousmuscles exist in batoids.

Euselachian: Referring to the Euselachii.

Euselachii: The cohort Euselachii (Greek Eu, true, good ororiginal, and selachos, shark or cartilaginous fish), the

spined or ‘phalacanthous’ sharks, including the modernsharks or Neoselachii, and fossil shark groups including thehybodonts, the ctenacanths, and the xenacanths, allprimitively with anal fins and having two dorsal fins with finspines.

Excurrent apertures: The posterior and ventrally facingopenings of the nostrils, which direct water out of the nasalcavities and which are often partially covered by the anteriornasal flaps. These are usually medial on the nostrils andposteromedial to the incurrent apertures, but may beposterior to the incurrent apertures only.

Exorhipidion: In claspers, a longitudinally elongated,external blade or flap with its base attached to thedorsolateral edge of the clasper glans, and with its free edgedirected medially. It is supported by the ventral terminal 2cartilage.

Eye notch: A sharp anterior or posterior indentation in theeyelid, where present cleanly dividing the upper and lowereyelids.

Filter screens: In the whale shark (Rhincodontidae) anddevil rays (Mobulidae), transverse bars with lateral dermallobes on the internal gill openings that form devices forscreening out plankton.

Fin skeletons: In unpaired precaudal fins, the basal platesand radials; in the caudal fin, the vertebral column includingexpanded neural and haemal arches; and in the paired fins,the fin girdles, basals, and radials.

Fin web: The usually thin, compressed part of the fin, distalto the base, that is supported by ceratotrichia alone (inaplesodic fins) or by ceratotrichia surrounding expanded finradials or by radials only (plesodic fin).

First dorsal constrictor muscles: Paired head musclesthat are confluent and functionally part of the levatorpalatoquadrati muscles in most nonbatoid sharks, except inorectoloboids where they are discrete muscles withseparate origins and insertions similar to but more lateralthan the levators.

First dorsal fin: The anteriormost dorsal fin of two, rangingin position from over the pectoral fin bases to far posterior onthe precaudal tail.

Foetus: A later development stage of the unborn young of alive-bearing shark, that essentially resembles a small adult.Term foetuses are ready to be born, and generally haveoral teeth and denticles erupting, have a colour pattern(often more striking than adults), and, in ovoviviparoussharks, have their yolk-sacs reabsorbed.

Foramen magnum: On the neurocranium, the ‘great hole’or posteromedial aperture through the occiput into thecranial cavity, above the occipital centrum and medial andusually dorsal to the occipital condyles. The spinal cordpasses from the brain through the foramen magnum into theneural canal of the vertebral column.

Free rear tips: The pectoral, pelvic, dorsal, and anal fins allhave a movable rear corner or flap, the free rear tip, that isseparated from the trunk or tail by a notch and an innermargin. In some sharks the rear tips of some fins are veryelongated.

Frontal and parietal fenestrae: On the neurocranium,medial apertures in the cranial roof between the anteriorfontanelle and the parietal fossa, the frontal fenestra beingcloser to the anterior fontanelle and the parietal fenestra tothe parietal fossa. Sometimes the two merge and become afrontoparietal fenestra, while in many batoids and in someorectoloboid sharks there is a merging of the anteriorfontanelle with the frontoparietal fenestra so that it extendsnearly to the parietal fossa. All of these fenestrae are closedby tough membranes.

Functional series: A series of oral teeth that are infunctional position on the jaw.

Galeomorph: Referring to the Galeomorphii.

Galeomorphii: The neoselachian superorderGaleomorphii, including the heterodontoid, lamnoid,orectoloboid, and carcharhinoid sharks.

Gill openings or slits: In elasmobranchs, the paired rows offive to seven transverse openings on the sides or undersideof the head for the discharge of water through the gills.Chimaeras have their four gill openings hidden by a soft gillcover and discharge water through a single external gillopening.

Gill-raker denticles: In the basking shark (Cetorhinidae),elongated denticles with hair-like cusps arranged in rows onthe internal gill openings, which filter out planktonicorganisms.

Gill-raker papillae: Sparse to dense dermal papillae on thegill arches of some sharks that serve as filters to collectsmall food organisms.

Girdle: A bar of cartilage buried in the body wall thatsupports the basals of the paired fins: the pectoral girdle(scapulocoracoid) and pelvic girdle (puboischiadic bar).

Haemal arch: The arch ventral to the notochord or vertebralcentra on tail vertebrae that is formed by the basiventralsand interventrals and which houses the caudal artery andcaudal vein in a haemal canal.

Haemal spines: On the haemal arches of thediplospondylous precaudal and caudal vertebrae, elongatedventral surfaces forming vertical plates, particularlywell-developed on the caudal fin.

Head: That part of a cartilaginous fish from its snout tip tothe last or (in chimaeras) only gill slits.

Heterocercal: A caudal fin with the vertebral axis slanteddorsally into the fin base, which is also dorsally elevated.

Heterodontoid: A bullhead shark, horn shark, or PortJackson shark, a member of the order Heterodontiformes,family Heterodontidae.

Heterodonty: In oral teeth, structural differences betweenteeth in various positions on the jaws, between teeth in thesame position during different life stages, or between teethin the same positions in the two sexes.

Hexanchoid: A cowshark or frilled shark, members of theorder Hexanchiformes, and including the sixgill sharks,sevengill sharks, and frilled sharks.

Holocephalan: Referring to the Holocephali.

Holocephali: The subclass Holocephali (from Greek holos,entire, and kephalos, head), the living chimaeras and theirnumerous fossil relatives, a major subdivision of the classChondrichthyes. The name is in reference to the fusion ofthe upper jaws or palatoquadrates to the skull in all livingspecies and in many but not all fossils. The livingholocephalans include three families in the orderChimaeri formes. The l iv ing species di ffer f romelasmobranchs in having four pairs of gill openings coveredby a soft gill cover and with a single pair of external gillopenings, oral teeth fused and reduced to three pairs ofever-growing tooth plates, an erectile first dorsal fin with aspine and a long, low spineless second dorsal.

Holotype: Either the only specimen used and mentioned inan original description of a species, with or without adesignation of such, or one of two or more specimens usedand mentioned in an original description of a species anddesignated as such. This becomes the ‘name-bearer’ of thespecies, and is used to validate the species or scientificname by anchoring it to a single specimen.

Homodonty: In oral teeth, structural similarity betweenteeth in various positions on the jaws, between teeth in thesame position during different life stages, or between teethin the same positions in the two sexes.

Hyoid arch: The visceral arch that supports the tongue and,in elasmobranchs, the rear of the upper jaws. The hyoid archis between the mandibular arch and the first branchial arch,and has the spiracular pocket between it and the mandibulararch. The hyoid arch in elasmobranchs includes a medialbasihyoid in the floor of the mouth and inside the tongue, apair of elongated ceratohyals articulating with the basihyoidand the hyomandibulae, and a pair of hyomandibulaearticulating with the ceratohyals and the hyomandibularfacets of the neurocranium. Chimaeroids have anonsuspensory hyoid arch similar to the gill arches, with apair of epihyals and pharyngohyals equivalent to thehyomandibulae. Batoids have the ceratohyals reduced andseparated from the hyomandibulars or absent, andfunctionally replaced by paired dorsal and ventralpseudohyoids.

Hyomandibular facet: On the neurocranium ofelasmobranchs, a joint surface, socket or cotyle that isusually on the ventrolateral surfaces of each otic capsule butmay be extended posteriorly or arched dorsally. The headsof the hyomandibulae articulate with these facets.Chimaeras lack hyomandibular facets and differentiatedhyomandibulae.

Hyomandibular nerve foramina: Foramina for the roots ofthe hyomandibular nerves, behind the orbital fissures.These foramina are confluent with the orbital fissure in manysharks.

Hypaxial web: The entire fin web below the vertebralcolumn (vertebral axis) and the caudal base.

Hypercalcified structures: Parts of the skeleton that havedeveloped extremely dense calcified cartilage, primarilyduring growth and maturation, which sometimes swell toknobs that distort and engulf existing cartilaginousstructures. The rostrum of the salmon shark (Lamnaditropis) is a particularly impressive hypercalcifiedstructure.



Hypocercal: A caudal fin with the vertebral axis slantedventrally into the fin base, which is also ventrally depressed.Found only in angel sharks (Squatiniformes) among livingsharks.

Hypopyle: On the external clasper and clasper skeleton,the posterior opening of the clasper groove onto the clasperglans.

Incurrent apertures: The anterior and ventrally facingopenings of the nostrils, which direct water into the nasalcavities. These are usually lateral on the nostrils andanterolateral to the excurrent apertures, but may be anteriorto the excurrent apertures only.

Independent dentition: Teeth along a mesodistal series inwhich the roots do not overlap and are separated by aspace. See overlapping dentition.

Inner margin: In precaudal fins including the pectoral,pelvic, dorsal and anal fins, the margin from the fin insertionto the rear tip.

Insertion: The posterior or rear end of the fin base inprecaudal fins. The caudal fin lacks insertions except withmany batoids and some chimaeroids that have a caudalfilament that extends posterior to the fin. See origin.

Interdorsal cartilages: A pair of wedge-shaped arched thincartilages fitting between the basidorsal cartilages of eachvertebra to complete the neural arch.

Interdorsal ridge: A ridge of skin on the midback of sharks,in a line between the first and second dorsal fins; particularlyimportant in identifying grey sharks (genus Carcharhinus,family Carcharhinidae).

Intermedialia: In a vertebral centrum, dorsal, ventral andlateral spaces between the attachment surfaces of thebasidorsal and basiventral cartilages and between the twohalves of the double cone. These can be filled withuncalcified cartilage, with solid or hollow wedges of calcifiedcartilage, or with plate-like, branched calcified radii withinuncalcified cartilage. See basalia.

Intermediate segments: In the clasper skeleton, one ormore short cylindrical cartilages connecting the pelvicbasipterygium to the axial cartilage of the clasper. Alsotermed stem-joints.

Intermediate teeth: Small oral teeth between the lateralsand anteriors of the upper jaw, found in most lamnoids.

Internasal plate or septum: On the neurocranium, a plateor partition between the two nasal capsules. It ranges from avertical plate to a broad horizontal plate.

Interventral cartilages: A pair of rounded or wedge-shapedcartilages fitting between the basiventral cartilages of eachvertebra, that in diplospondylous precaudal and caudalvertebrae form the haemal arches with the basiventralcartilages.

Intestinal valve: A dermal flap inside the intestine,protruding into its cavity or lumen, and of various forms indifferent cartilaginous fishes. Often formed like a corkscrewor augur. See spiral, ring and scroll valves.

Jaws: See mandibular arch.

Labial cartilages: Paired cartilages that are internal andsupport the labial folds at the lateral angles of the mouth.Living neoselachians typically have two pairs of upper labialcartilages, the anterodorsal and posterodorsal labialcartilages, and one pair of ventral labial cartilages, butthese are variably reduced and sometimes absent in manysharks. Chimaeras have more elaborate labial cartilagesthan living elasmobranchs.

Labial flange: On tooth crowns of many squaloids andsome orectoloboids, a narrow, vertically elongated labialbasal ledge.

Labial folds: Lobes of skin at the lateral angles of themouth, usually with labial cartilages inside them, separatedfrom the sides of the jaws by pockets of skin (labial groovesor furrows).

Labial furrows or labial grooves: Grooves around themouth angles on the outer surface of the jaws of manycartilaginous fishes, isolating the labial folds. Primitivelythere is a distinct upper labial furrow above the mouthcorner and a lower labial furrow below it.

Labial: In oral teeth, the outer face of the tooth that isdirected outside the mouth and towards the lips. Seelingual.

Lamnoid: A mackerel shark, a member of the orderLamniformes, and including the sand tiger sharks, goblinsharks, crocodile sharks, megamouth shark, threshersharks, basking shark, and the makos, porbeagle, salmonshark and white shark.

Lateral clasper fold: In mackerel sharks (family Lamnidae),a unique longitudinal flap of skin along the lateral edge of theexternal clasper shaft.

Lateral commissures: On the neurocranium, tube-like orring-like enclosed passages for the lateral head veins, whichdrain the orbital sinuses, through the postorbital walls of theorbits and below the sphenopterotic ridges and above thehyomandibular facets in neoselachians. The lateralcommissures are reduced or absent in many livingneoselachians.

Lateral or laterad: Outwards, in the transverse directiontowards the periphery of the body. See medial.

Lateral orolabial grooves: Shallow longitudinal grooves onthe lower jaw that connect the edge of the lip on each sidewith the medial ends of the lower labial furrows. Found inmore advanced orectoloboids.

Lateral teeth: Large broad-rooted, compressed, highcrowned oral teeth on the sides of the jaws between theanteriors and posteriors.

Lateral trunk denticle: A dermal denticle from thedorsolateral surface of the back below the first dorsal finbase.

Lectotype: One of two or more specimens that weresyntypes in an original description, designated as alectotype by a subsequent writer. It then becomesequivalent to a holotype, and anchors the name of thespecies to a specimen unless invalidated by a ruling of theInternational Commission on Zoological Nomenclature or aprevious designation of a lectotype.

Levator palatoquadrati muscles: Paired head musclesthat primitively originate on the underside of the postorbitalprocesses and sphenopterotic ridges, extend vertically, andinsert on the posteromedial surfaces of the quadrateprocesses of the palatoquadrates. In advancedcarcharhinoids the origins of the levator palatoquadratimuscles are expanded far forwards and diagonally into theorbits. Primitively these muscles lift or retract the jawsupwards, but in advanced carcharhinoids may help rotatethe jaws forwards and downwards in opposition to thelevator hyomandibularis muscles, which retract the jaws.

Lingual: In oral teeth, the inner face of the tooth that isdirected inside the mouth and towards the tongue. Seelabial.

Live-bearing: A mode of reproduction in which femalesharks give birth to young sharks, which are miniatures ofthe adults. See viviparity.

Longitudinal ridges: In lateral trunk denticles, parallelridges that extend anteroposteriorly on the distal surface ofthe crown. These may be in the form of a single medialridge (sometimes paired), and paired lateral ridges, andmay terminate in medial and lateral cusps.

Lower eyelid: The ventral half of the eyelid, separated by adeep pocket (conjunctival fornix) from the eyeball. In somederived batoids the pocket also fuses with the eyeball.

Lower origin: In the caudal fin, the anteroventral beginningof the hypaxial or lower web of the caudal fin, at the posteriorend of the anal-caudal or pelvic-caudal space (seemeasurement illustrations).

Lower postventral margin: In the caudal fin, the lower partof the postventral margin of the hypaxial web, from theventral tip to the posterior notch.

Mandibular arch: The paired primary jaw cartilages ofsharks, including the dorsal palatoquadrates and the ventralMeckel’s cartilages.

Mandibulocutaneous muscles: Paired head muscles insqualoid and hexanchoid sharks, that originate on the insideof the skin of the head behind the eyes and near thespiracles, and insert on the dorsoposterolateral face of thequadrate processes of the palatoquadrates.

Meckel’s cartilages: The paired lower jaw cartilages,articulating mesially with each other at the midline orsymphysis of the lower jaw, and articulating laterally with thedistal ends of the palatoquadrates. The Meckel’s cartilagesare fused together at the symphysis in some shark-likefishes or are articulated to a symphysial cartilage in others.

Medial teeth: Small oral teeth, generally symmetrical andwith narrow roots, in one row at the symphysis and often inadditional paired rows on either side of the symphysial one.

Medial: Inwards, in the transverse direction towards themiddle of the body. See lateral.

Mesial: In oral teeth, mesial structures are towards themidlines of the jaws, the symphyses. See distal.

Mesopterygium: In the pectoral fin skeleton of livingneoselachians, the middle basal cartilage, between thepropterygium and metapterygium. The mesopterygium is

sometimes fused to the propterygium or metapterygium, orto both.

Mesorhipidion: A knife-like or blade-like structure on thelateral clasper glans of some carcharhinoid sharks, formedfrom the terminal 3 cartilage, and over and partially lateral tothe ventral terminal and mesial to the pseudopera.

Metapterygial axis: In the pectoral fin skeleton of livingneoselachians, the poster ior extension of themesopterygium as a flattened, elongated segmented seriesof cartilages that supports the distal bases and free rear tipsof the pectoral fins; the axis has radials along its distal edgecontinuous with the radials on the metapterygial basal.

Metapterygial basal: In the pectoral fin skeleton of livingneoselachians, the anteriormost, expanded cartilage of themetapterygium.

Metapterygial proximal segment: In the hexanchoidpectoral fin skeleton, a short jointed segment on theproximal end of the metapterygial basal, not found in othersharks.

Metapterygium: In the pectoral fin skeleton of livingneoselachians, the rearmost basal cartilage, adjacent to theposterior edge of the mesopterygium and with severalradials attached to its distal edge. It includes themetapterygial basal and the metapterygial axis.

Molariform: In oral teeth, referring to a tooth with a broadflat crown with low cusps or none, for crushing hard-shelledinvertebrate prey.

Monospondylous precaudal vertebrae: Vertebrae withone centrum and one pair of basidorsals, basiventrals, andribs per body segment (myotome), and generally extendingfrom the occiput to the end of the body cavity and to over thepelvic girdle. However there is much variation in the positionof the monospondylous-diplospondylous transition, whichcan range well in front or behind the pelvic girdle.

Monospondylous-diplospondylous transition: Theposition on the vertebral column where monospondylouscentra end and diplospondylous centra begin. In lateral viewthe transition often appears as an abrupt decrease in lengthof the diplospondylous centrum compared to the lastmonospondylous centrum, but this can be obscure invarious sharks with very numerous, very short centra. Oftena centrum of intermediate length appears between a longmonospondylous centrum and a short diplospondylouscentrum. In a few sharks there is a stutter zone ofalternating long and short centra that marks the transition.Also, the basidorsals and basiventrals have foramina for thespinal nerves on every other vertebra, rather than on eachvertebra as in monospondylous vertebrae. The transitionfrom long to short centra is generally coordinated with thetransition of vertebrae with free ribs and no haemal arches tothose without ribs and with haemal arches. However, insome sharks the two transitions can be anterior or posteriorto each other.

Multiple oviparity: A mode of egg-laying or oviparity inwhich female sharks retain several pairs of cased eggs inthe oviducts, in which embryos grow to advanceddevelopmental stages. When deposited on the bottom (incaptivity) the eggs may take less than a month to hatch.Found only in the scyliorhinid genus Halaelurus, with someuncertainty as to whether the eggs are normally retained in



the oviducts until hatching. Eggs laid by these sharks maybe abnormal, unusual, or an alternate to ovoviviparity. Thewhale shark (Rhincodon typus) may have multiple retentionof egg cases; near-term foetuses have been found in theiruteri and egg-cases with developing foetuses have beencollected on the bottom.

Nasal aperture: On the neurocranium, an aperture in theanteroventral surface or floor of each nasal capsule, throughwhich the nostril directs water into and out of the nasalorgan.

Nasal capsules: On the neurocranium, a pair of spherical,oval or trumpet-shaped, thin-walled structures behind therostrum (when present) and in front of the orbits, cranial roofand basal plate. They serve as containers for the nasalorgans or organs of smell, and have passages into thecranial cavity to connect the nasal organs with the brain.

Nasal curtain: Anterior nasal flaps that are expandedmedially and posteriorly and have fused with each other.Nasal curtains are found in some carcharhinoid sharks andin many batoids.

Nasal flap: One of a set of dermal flaps associated with thenostrils, and serving to direct water into and out of them,including the anterior, posterior, and mesonarial flaps.

Nasal fontanelle: On the neurocranium, an aperture in theposteroventral surface or floor of each nasal capsule,behind the nasal apertures and closed by a dermalmembrane.

Nasoral grooves: Many bottom-dwelling, relatively inactivesharks have nasoral grooves, shallow or deep grooves onthe ventral surface of the snout between the excurrentapertures and the mouth. The nasoral grooves are coveredby expanded anterior nasal flaps that reach the mouth, andform water channels that allow the respiratory current to pullwater by partial pressure into and out of the nostrils and intothe mouth. This allows the shark to actively irrigate its nasalcavities while sitting still or when slowly moving. Nasoralgrooves occur in heterodontoids, orectoloboids,chimaeroids, some carcharhinoids, and most batoids. Alsotermed oronasal grooves.

Neck: A narrow band of finely porous dull tissue (possiblyorthodentine) encircling the proximal end of the crown of atooth, and apparently covered with dental membrane.

Neoselachian: Referring to the Neoselachii.

Neoselachii: From Greek neos, new, and selachos, shark.The modern sharks, the subcohort Neoselachii, consistingof the living elasmobranchs and their immediate fossilrelatives. See Euselachii.

Neotype: A specimen, not part of the original type series fora species, which is designated by a subsequent author,particularly if the holotype or other types have beendestroyed, were never designated in the original description,or are presently useless.

Neural arch: In shark vertebrae, a dorsal arch formed bybasidorsal and interdorsal cartilages above the centrum andforming a neural canal containing the spinal cord.

Neural spines: On the neural arches of shark vertebrae,elevated dorsal plate- l ike surfaces, part icular lywell-developed in many squalomorph sharks.

Neurocranium: In sharks, a box-shaped complexcartilaginous structure at the anterior end of the vertebralcolumn, containing the brain, housing and supporting thenasal organs, eyes, ears, and other sense organs, andsupporting the visceral arches or splanchnocranium. Alsotermed chondrocranium, chondroneurocranium, orendocranium.

Nictitating lower eyelid: In the ground sharks (orderCarcharhiniformes), a movable lower eyelid that has specialposterior eyelid muscles that lift it and, in some species,completely close the eye opening (or palpebral aperture).Often incorrectly termed nictitating membrane, a different,nonhomologous structure in terrestrial vertebrates.

Nictitating upper eyelid: In parascylliid orectoloboids, theupper eyelid has anterior eyelid muscles that pull it downand close the eye opening, analogous to the nictitating lowereyelids of carcharhinoids.

Nomenclature: In biology, the application of distinctivenames to groups of organisms.

Nostrils: The external openings of the cavities of the nasalorgans, or organs of smell.

Notochord: In embryonic sharks (and other chordates) thenotochord is a fluid-filled tube below the spinal cord that hasa connective-tissue notochordal sheath surrounding it. Thenotochord forms the primitive developmental base of thechondrichthyan vertebral column. Chimaeroids retain thenotochord and its sheath without constriction (althoughsome have ring-like centra in the sheath), but inneoselachians it is constricted by the development ofdouble-cone calcifications of the centra within the sheathinto biconical chambers between each centrum. Theaddition of centra to the notochordal sheath strengthens thevertebral column. Some deepwater squaloid, hexanchoid,and lamnoid sharks have the sheath constriction andcalcified double cones variably reduced, sometimes toconnective tissue septa only. Some of these taxa with a‘notochordal’ vertebral column have been consideredprimitive but are apparently derived from ancestors withwell-calcified, constricted vertebral centra.

Occipital centrum: On the occiput of the neurocranium, theposterior half of a calcified double cone of the vertebralcolumn, imbedded in the basal plate and articulating with theanteriormost centrum of the vertebral column. Also termedoccipital hemicentrum.

Occiput: The posteriormost sector of the neurocranium,behind and partially between the otic capsules, with itsdorsal surface from the parietal fossa rearwards to theforamen magnum, and its posterior surface including theoccipital condyles, the occipital centrum, the paired vagusnerve foramina, the paired glossopharyngial nerveforamina, and the rear surface of the hyomandibular facets.

Ocelli or eyespots: Large eye-like pigment spots locatedon the dorsal surface of the pectoral fins or bodies of somesharks including rays, angel sharks, and some bamboosharks, possibly serving to frighten potential enemies.

Oophagy: From Greek oön, egg, and phagos, to eat.Egg-eating, a mode of live-bearing reproduction employinguterine cannibalism; early foetuses deplete their yolk-sacksearly and subsist by eating nutritive eggs produced by themother. Known in several lamnoid sharks, the carcharhinoidfamily Pseudotriakidae, and in the orectoloboid familyGinglymostomatidae (Nebrius ferrugineus).

Optic nerve foramen: A large foramen usually in the middleof the orbital wall, passing the optic nerve from the brain tothe eye.

Optic pedicel: On the neurocranium, a slender cartilagethat projects from the medial orbital wall and articulates withthe eyeball; it serves as a pivot point for the eyeball and aspacer between the eyeball and the orbital wall.

Orbital fissures: The main foramina or fenestrae that passthe trigeminal and facial nerves from the brain to the orbits,located on the posteroventral ends of the medial walls of theorbits.

Orbital notches: On the neurocranium, the paired anteriornotches in the suborbital shelves that articulate with theorbital processes of the palatoquadrates. In manysqualomorph sharks these are enlarged, deepened,socket-like, and posteriorly situated in the orbits, withtelescoping of the suborbital shelves, and are lost in batoids.

Orbits: Large, paired cavities on the sides of theneurocranium, behind the nasal capsules, mostly in front ofthe otic capsules, and separated medially by the cranialcavity. They are bounded anteriorly by the preorbital wallsand processes, dorsally by the supraorbital crests, ventrallyby the suborbital shelves (reduced or lost in varioussqualomorphs), and posteriorly by the postorbital processesand walls. The orbits contain the eyeballs and their muscles,venous sinuses, several arteries that connect to the cranialcavity, and most of the cranial nerves.

Orectoloboid: A carpet shark, a member of the orderOrectolobiformes, including barbelthroat carpet sharks,blind sharks, wobbegong sharks, bamboo sharks, epaulettesharks, nurse sharks, zebra sharks, and whale sharks.

Origin: The anterior or front end of the fin base in all fins.The caudal fin has upper and lower origins but no insertion.See insertion.

Orthodentine: A primary hard tissue comprising the crownof oral teeth in sharks, with numerous fine mostly parallelnonvascular tubules.

Orthodont: An oral tooth with its crown filled withorthodentine, and with a prominent central pulp cavity.

Osteodentine: A primary hard tissue comprising the rootsand sometimes the inside of the crown in the oral tooth, withbone-like large reticulating, thick-walled tubules.

Osteodont: An oral tooth with its crown filled withosteodentine, continuous with the root, and without a pulpcavity.

Otic capsules: On the neurocranium, a pair of complexthick-walled capsules containing the inner ears, and locatedbetween the orbits and the occiput, and partially separatedmedially by the cranial cavity.

Overlapping dentition: Teeth along a mesodistal series inwhich the roots overlap and are not separated by a space.Two types of overlap patterns occur, alternate overlap, inwhich teeth in a series alternate from more labial to morelingual, and imbricate overlap, in which the distal end ofeach tooth lingually or labially overlaps the mesial end of thesucceeding tooth, repeating to the distal ends of the dentalband. Alternate-imbricate dentitions combine bothalternate and imbricate overlap. See independentdentition.

Oviparity: A mode of reproduction in which female sharksdeposit eggs enclosed in oblong or conical egg-cases on thebottom, which hatch in less than a month to more than ayear, producing young sharks which are miniatures of theadults.

Ovoviviparity: Generally equivalent to yolk-sac viviparity,live-bearing in which the young are nourished primarily bythe yolk in the yolk-sac, which is gradually depleted and theyolk-sac reabsorbed until the young are ready to be born.Sometimes used to cover all forms of aplacental viviparity,including cannibal viviparity.

Paired fins: The pectoral and pelvic fins.

Palatoquadrates: The paired upper jaw cartilages,articulating mesially with each other at the midline orsymphysis of the upper jaw, and articulating laterally with thedistal ends of the Meckel’s cartilages. The palatoquadratesare fused to the neurocranium in all living holocephalans.The palatoquadrates of neoselachians are divided intocylindrical anteromedial sectors or palatine processes,which articulate or are otherwise attached to each other atthe symphysis; variably modified conical to flattenedarticular structures or orbital processes on the middle ofthe palatoquadrates for attachment to the neurocranium atthe orbital notches; and often elevated posterodistalquadrate processes that articulate with the distal ends ofthe Meckel’s cartilages and are loosely or firmly attached tothe distal ends of the hyomandibulae. In a few livingneoselachians, and many fossil elasmobranchs, thequadrate processes have postorbital articulations withthe rear surfaces of the postorbital processes of theneurocranium.

Palpebral aperture: The eye opening, defined by the upperand lower eyelids.

Papillae: Elongated finger-like processes of skin, locatedaround the spiracles of torpedo rays, and in the mouths andon the gill arches of other sharks.

Papillose gill rakers: See gill raker papillae.

Paralectotype: One of two or more specimens that weresyntypes in an original description, but which became aparalectotype or paralectotypes when a subsequent authordesignated one of the syntypes as a lectotype.Paralectotypes are equivalent to paratypes.

Paratype: Each specimen of a type series other than theholotype. Specimens other than the holotype automaticallybecome paratypes unless the author designates them asreferred specimens that are not part of the type series.

Parietal fossa: On the neurocranium, a shallow or deepdepression between the otic capsules and at the rear of the



cranial roof, that houses foramina for paired ducts leading tothe inner ears and for the spaces around them.

Pectoral fins: A symmetrical pair of fins on each side of thetrunk just behind the head and in front of the abdomen.These are present in all cartilaginous fishes and correspondto the forelimbs of a land vertebrate (a tetrapod orfour-footed vertebrate).

Pectoral or shoulder girdle: See scapulocoracoid.

Pedicel: In lateral trunk denticles, a narrow stalk separatingthe crown from the base.

Pelvic fin: A symmetrical pair of fins on the sides of the bodybetween the abdomen and precaudal tail which correspondto the hindlimbs of land vertebrate (a tetrapod or four-footedvertebrate). Also, ventral fins.

Pelvic girdle: See puboischiadic bar.

Photophores: Conspicuously pigmented small spots on thebodies of most lantern sharks (family Etmopteridae) andsome kitefin sharks (family Dalatiidae). These are tiny roundorgans that are covered with a conspicuous dark pigment(melanin) and produce light by a low-temperature chemicalreaction.

Placenta: See yolk-sac placenta.

Placental viviparity: Live-bearing in which the youngdevelop a yolk-sac placenta, which is apparently confined tothe carcharhinoid sharks.

Placoid scale: See dermal denticle.

Plesodic fin: A pectoral, pelvic, dorsal, or anal fin in whichthe radial cartilages of the fin skeleton extend far into thedistal fin web, often near its edges, and between thesupporting ceratotrichia of the fin web. Some fossil sharksalso have plesodic caudal fins, in which the expandedhaemal arches of the caudal vertebrae extend far into the finweb. In more advanced batoids the radials of the plesodicpaired fins become highly branched and segmented, verynarrow and slender, and essentially replace the ceratotrichiaas supports for the fin webs.

Pores, pigmented: In a few sharks and skates, the poresfor the lateral line and ampullae of Lorenzini areconspicuously black-pigmented, and look like little blackspecks.

Posterior: Rearwards, in the longitudinal direction of thecaudal-fin tip or tail filament. Also caudal.

Posterior margin: In precaudal fins, the margin from the finapex to either the free rear tip (in sharks with distinct innermargins) or the fin insertion (for those without innermargins).

Posterior nasal flaps: Low flaps or ridges arising on theposterior edges of the excurrent apertures of the nostrils.

Posterior notch: In the caudal fin, the notch in thepostventral margin dividing it into upper and lower parts.

Posterior teeth: Small or sometimes enlarged irregular oralteeth near and at the distal ends of the dental bands, withlow crowns and sometimes missing cusps.

Posterior tip: The posteriormost corner or end of theterminal lobe of the caudal fin.

Postocular eyelid muscles: A complex of paired headmuscles unique to carcharhinoid sharks that originatearound the spiracles and insert on the posterior ends of theupper eyelids and nictitating lower eyelids. Primitively theydepress the upper eyelid and elevate the nictitating lowereyelid to close the eye, but in more derived carcharhinoidsthe eye is closed only by elevation of the nictitating lowereyelid.

Postorbital processes: On the neurocranium,posterolateral projections of the supraorbital crests, belowwhich the postorbital walls originate.

Postorbital walls: On the neurocranium, the posteriorboundaries of the orbits, variously reduced vertical plates ofcartilage that close the orbits between the postorbitalprocesses and the suborbital shelves, more or less reducedin living neoselachians.

Postventral margin: In the caudal fin, the margin from theventral tip to the subterminal notch of the caudal fin. Seelower and upper postventral margins.

Preanal ridges: A pair of low, short to long, narrow ridges onthe midline of the caudal peduncle extending anteriorly fromthe anal fin base.

Precaudal fins: All fins in front of the caudal fin.

Precaudal pit: A depression at the upper and sometimeslower origin of the caudal fin where it joins the caudalpeduncle.

Precaudal tail: That part of the tail from its base at the ventto the origins of the caudal fin.

Precaudal vertebrae: Vertebrae from the occiput to thedorsal origin of the caudal fin.

Predorsal ridge: A low narrow ridge of skin on the midline ofthe back anterior to the first dorsal fin base.

Preorbital canals: On the neurocranium, anterior passagesfor the superficial opthalmic nerves out of the orbits and ontothe nasal capsules and rostrum, situated at the anteromesialedges of the supraorbital crests at the rear bases of thepreorbital processes; sometimes greatly expandedposteriorly.

Preorbital processes: On the neurocranium, anterolateralprojections of the supraorbital crests, below which thepreorbital walls originate.

Preorbital walls: On the neurocranium, the anteriorboundaries of the orbits, curved vertical plates of cartilagethat vary from complete to absent in neoselachians.

Preorbitalis muscles: Paired head muscles that primitivelyoriginate on the rear of the nasal capsules or on thepreorbital walls, run diagonally rearwards, and insert on theadductor mandibulae at the mouth angles. Orectoloboidsand heterodontoids have the preorbitalis vertical, withcross-biased fibres in the latter, and the insertions are alongthe ventral edge of Meckel’s cartilage. In derivedorectoloboids the origins of the preorbitalis are expandedonto the cranial roof and the muscles greatly expanded.

Primitively the preorbitalis may primarily serve to protrudethe jaws, but they may primarily serve to increase the powerof the bite in orectoloboids and heterodontoids. Also termedlevator labii superioris muscles.

Preventral margin: In the caudal fin, the margin from thelower origin to the ventral tip of the caudal fin.

Pristiophoroid: A saw shark, order Pristiophoriformes,family Pristiophoridae.

Propterygium: In the pectoral fin skeleton of livingneoselachians, the anteriormost basal cartilage, adjacent tothe anterior edge of the mesopterygium and with one ormore radials attached to its distal end. In batoids withexpanded anterior pectoral fin lobes it becomes expandedand segmented into a propterygial basal and propterygialaxis, similar to the metapterygial basal and axis.

Proximal: In any direction, at the near end of a structure.

Pseudopera: On the external clasper glans, a dorsallyopening blind pocket along the lateral edge of the clasper,and about opposite the anterior edge of the glans.

Pseudosiphon: On the external clasper glans, a dorsallyopening blind pocket along the medial edge of the clasper,and about opposite the cover rhipidion.

Pterotic horn or process: On the neurocranium, elongatedposterior projections of the sphenopterotic ridges of the oticcapsules.

Puboischiadic bar: A transverse flattened or cylindricalplate in the posterior body wall opposite the anterior ends ofthe pelvic fins, in front of the vent and at the posterior end ofthe body cavity, that supports a few anterior pelvic radialsand a basal cartilage, the basipterygium. The pelvic girdle.

Radial cartilages or radials: The small, segmented, moredistal cartilages of the precaudal fins, attached proximally tothe distal edges of the basal cartilages. In the pectoral finskeleton of living neoselachians, the radials mostly havethree segments but range from no segments to 30 or more.The radial segments adjacent to the pectoral basals are theproximal radials, the radial segments furthest from thebasals are the distal radials, and any segments betweenthem are intermediate radials.

Radii: In a vertebral centrum in cross-section, branchingplates of calcified cartilage in the intermedialia. These havea radial orientation from the centre of the centrum.

Ray: See batoid.

Replacement series: A series of oral teeth that are lingualto the functional series, and not in a functional position onthe jaw.

Rhipidion: In nonbatoid sharks, a longitudinal, elongatedflap attached to the floor of the glans along its base and withits free edge directed laterally. In skates (Rajoidei) rhipidionis used for a soft mass of erectile tissue in the glans, notnecessarily homologous to the rhipidion of nonbatoidsharks.

Rhomboidal: In the form of a rhombus or diamond.

Ribs: On the shark vertebral column, short to elongatedpaired and typically pointed cartilages attached to the

basiventral cartilages and extending into the horizontalseptum of the segmented trunk musculature or myomeres.Chondrichthyan ribs are therefore dorsal ribs rather thanventral ribs as in bony fishes (which support the bodycavity).

Ring valve: A type of spiral intestinal valve in which thevalve turns are very numerous and short and resemble astack of washers.

Root lobe: Sharks often have the roots of their oral teethdivided into separate lobes at their midlengths, which aretermed mesial and distal root lobes.

Root: The proximal part of the oral tooth, made of porousosteodentine and anchoring the tooth in the dentalmembrane of the jaw.

Rostral keel: In the neurocranium of squaloids, a largevertical plate on the underside of the rostrum and internasalseptum, sometimes reduced, and with the cavities of thesubnasal fenestrae on either side of the keel.

Rostral node: On the neurocranium, the anterior end of therostrum of cartilaginous fishes, and the plate formed by thefused anterior ends of the tripodal rostra in manygaleomorph sharks.

Rostromandibular muscle: In the orectoloboid familyParascylliidae, paired head muscles that originate on thesides of the adductor mandibulae muscles and insert vialong tendons on the medial rostral cartilage. These arepossibly for depressing the snout. Not found in any othersharks, though analogous muscles exist in batoids.

Rostronuchal muscles: In the orectoloboid familyParascylliidae, paired head muscles that originate on thedorsal myomeres of the nape, and insert via long tendons onthe medial rostral cartilage. These are possibly for elevatingthe snout. Not found in any other sharks, though analogousmuscles exist in batoids.

Rostrum: On the neurocranium, the cartilaginousanteriormost structure which supports the prenasal snoutincluding lateral line canals and masses of ampullae, and islocated in front of the nasal capsules and anterior fontanelle.The rostrum is very variable, and in squalomorph sharks isprimitively trough or basin-shaped, while it may beprimitively rod-shaped or tripodal in galeomorph sharks. It isabsent in a few nonbatoid sharks and in many batoids. Seerostrum, tripodal.

Rostrum, tripodal: The rostrum of the neurocranium inlamnoid and carcharhinoids is primitively tripodal, with a pairof dorsolateral lateral rostral cartilages that arise from theposterolaterodorsal surfaces of the nasal capsules or fromthe preorbital wall, and a medial rostral cartilage thatarises from the anteromedial surface of the internasalseptum. The medial and lateral rostral cartilages extendanteriorly and articulate or fuse at the rostral node. Livingorectoloboids have only the medial rostral cartilage althougha tripodal rostrum may be present in some fossilorectoloboids, while heterodontoid sharks lack a rostrum asadults but apparently lose it as embryos.

Row: In oral teeth, a single replicating line of teeth,approximately transverse to the longitudinal jaw axis, whichincludes functional teeth and their replacements, derivedfrom one tooth-producing area on the jaw.



Saw or saw-snout: The elongated snout in sawfish andsawsharks, with side and (in sawsharks) ventral teethformed from enlarged denticles, used to kill, ensnare or digfor prey. Also termed rostral saw.

Scapulocoracoid: The primitively U-shaped cartilage in thebody wall just behind the gills and at the anterior end of thepectoral bases, that supports the pectoral fins andarticulates with the pectoral basals. The scapulocoracoidconsists of a ventral coracoid bar connecting its pairedlateral faces with articular condyles or ridges for thepectoral basals, and a pair of dorsal scapular processesdorsal to the lateral faces. The scapular processessometimes have separate suprascapulae above them, butthey are sometimes fused with the scapular processes. Thecoracoid bar has a medial joint or even a separate medialcartilage (sternal cartilage) in a few living sharks, as withmany fossil cartilaginous fishes. The pectoral or shouldergirdle.

Scroll valve: A type of spiral intestinal valve in requiem andhammerhead sharks in which the valve has uncoiled andresembles a rolled-up bib or scroll.

Second dorsal fin: The posteriormost dorsal fin of two incartilaginous fishes, ranging in position from over the pelvic-fin bases to far posterior on the precaudal tail.

Secondary caudal keels: Low horizontal dermal keels onthe ventral base of the caudal fin in mackerel sharks(Lamnidae) and sometimes somniosids.

Secondary lower eyelid: The eyelid below or lateral to thenictitating lower eyelid, separated from it by a suboculargroove or pocket, and, in many carcharhinoids with internalnictitating lower eyelids, functionally replacing them as lowereyelids. Some orectoloboids have shallow suboculargrooves separating their non-nictitating lower eyelids fromweakly developed secondary lower eyelids. They may,however, be able to close their eye openings by retractingthe eyeballs.

Semiplesodic fin: In some sharks, a pectoral or dorsal finwith the fin radial cartilages extending partway into the finweb but not to its distal edges, essentially intermediatebetween plesodic and aplesodic fins.

Series: In oral teeth, a line of teeth along the jaws which isparallel to the jaw axis and includes teeth from all rowspresent.

Serrations: In oral teeth, minute teeth formed by the cuttingedge of the crown that enhance the slicing abilities of theteeth.

Shark: Generally used for cylindrical or flattenedcartilaginous fishes with 5 to 7 external gill openings on thesides of their heads, pectoral fins that are not attached to thehead above the gill openings, and a large, stout tail with alarge caudal fin; that is, all living elasmobranchs except therays or batoids. Living sharks in this sense are all membersof the Neoselachii, the modern sharks and rays. Shark isalso used loosely for fossil chondrichthyans that are notneoselachians but have a shark-like form, and even for‘spiny sharks’ (acanthodians) and for certain teleosts. Raysare essentially flattened sharks with the pectoral finsattached to their heads and are cladistically nested withinthe squalomorph sharks, while living chimaeras are theimmediate sister group of living neoselachians and are

called ghost sharks or silver sharks. Hence shark is usedhere in an alternate and broader sense to include the raysand chimaeras.

Shoulder: In oral teeth, an arcuate or straight,convex-edged section of the crown foot, without cuspletsand similar to a blade but without a cutting edge.

Single oviparity: A mode of egg-laying or oviparity in whichfemale sharks produce encased eggs in pairs, which are notretained in the oviducts and are deposited on the bottom.Embryos in the egg-cases are at an early developmentalstage, and take a few months to over a year to hatch. Foundin almost all oviparous cartilaginous fishes.

Siphons: A pair of dermal sacs in the ventral abdominal wallof male sharks, connecting posteriorly with the apopyles ofthe claspers, and extending anteriorly a variable distancefrom about opposite the pelvic origins to opposite thepectoral bases.

Skull or cranium: The skull or head skeleton of sharksincludes the neurocranium and the splanchnocranium orvisceral arches. The visceral arches articulate with and areassociated with the neurocranium, but, except for the upperjaws of many holocephalans, are not fused to it. Also termedsyncranium.

Snout: That part of a cartilaginous fish in front of its eyesand mouth, and including the nostrils.

Sphenopterotic ridge: On the neurocranium, a horizontalridge along the dorsolateral edge of each otic capsule thateither ends at the occiput or terminates in an expandedpterotic process.

Spiracle: A small to large opening between the eye and firstgill opening of most sharks and rays, representing themodified gill opening between the jaws and hyoid (tongue)arch. This is secondarily lost in chimaeras and some sharks.

Spiral or conicospiral valve: An intestinal valve shapedlike a corkscrew or augur, with the valve angled anteriorlyand medially in the intestine.

Splanchnocranium: That part of the shark skull includingthe visceral arches. These include the jaws or mandibulararch, the tongue or hyoid arch, and the five to seven gill orbranchial arches. Also, viscerocranium.

Squalene: A long-chain oily hydrocarbon present in the liveroil of deepwater cartilaginous fishes. It is highly valued forindustrial and medicinal use.

Squaloid: A dogfish shark, a member of the orderSqualiformes, including bramble sharks, spiny dogfish,gulper sharks, lantern sharks, viper sharks, rough sharks,sleeper sharks, kitefin sharks, and cookiecutter sharks.

Squalomorph: Referring to the Squalomorphii.

Squalomorphii: The neoselachian superorderSqualomorphii, including the hexanchoid, squaloid,squatinoid, pristiophoroid, and batoid sharks.

Squatinoid: An angel shark, order Squatiniformes, familySquatinidae.

Squatinoid caudal fin: Angel sharks (Squatiniformes) areunique among living sharks in having hypocercal caudal fins

that resemble inverted caudal fins of ordinary sharks. Thedorsal margin is subdivided into a predorsal margin fromthe upper origin to its dorsal tip (analogous to the preventralmargin and ventral tips in ordinary sharks), a postdorsalmargin (like the postventral margin) from the dorsal tip to itssupraterminal notch (similar to the subterminal notch), and ashort supraterminal margin and large ventral terminalmargin (similar to the subterminal and terminal margins)between the supraterminal notch and the ventral tip of thecaudal. The ventral margin has a preventral margin forminga ventral lobe with the ventral tip and the ventral terminalmargin.

Stapedial foramen or fenestra: On the neurocranium, aforamen through the posteroventromedial surface of eachsuborbital shelf into the orbit, for the stapedial or orbitalarteries. It may be greatly expanded into a stapedial fenestrain sharks with greatly coiled stapedial arteries or lost insharks with the suborbital shelves greatly reduced orabsent.

Stapediocarotid foramen: On the neurocranium of certainsharks, fusion of the stapedial and carotid foramina on eitherside produces a single pair of stapediocarotid foramina.

Subcaudal keel: In a few dogfish sharks (familyCentrophoridae), a single longitudinal dermal keel on theunderside of the caudal peduncle.

Subethmoid fossa: On the neurocranium, a deep cavity onthe ventral surfaces of the nasal capsules and the internasalplate, into which fit the palatine processes of the upper jaws.

Subnasal fenestrae: On the neurocranium of squaloids, apair of apertures in the internasal plate between the nasalcapsules that connect the cerebral cavity with two ventralfluid-filled cavities between the nasal capsules and therostral keel. The fenestrae themselves are covered by toughmembranes as with the anterior fontanelle. Subnasalfenestrae are present in most squaloids but reduced in a fewderived species, and are not found in other sharks. Theirfunction is obscure but may be sensory. Also termed basalcommunicating canals.

Suborbital shelf: On the neurocranium, a horizontal platearising on the ventral junction of the orbital wall and basalplate on each side which extends from the nasal capsule tothe otic capsule; it forms the floor of the orbit. Awell-developed suborbital shelf is apparently primitive forshark-like fishes but is variably telescoped, reduced or lostin many squalomorph sharks and a few galeomorphs.

Subterminal margin: In the caudal fin, the margin from thesubterminal notch to the ventral beginning of the terminalmargin.

Subterminal mouth or ventral mouth: Mouth located onthe underside of the head, behind the snout. Also termed aninferior mouth, in reference to its ventral position but not itsfunction. A superior mouth (not found in living cartilaginousfishes) is on the dorsal surface of the head.

Subterminal notch: On the caudal fin of most nonbatoidsharks and at least one batoid, the notch in the lower distalend of the caudal fin, between the postventral andsubterminal margins, and defining the anterior end of theterminal lobe.

Superficial ophthalmic nerve foramina: Foramina for theroots of the superficial ophthalmic nerves in the medial wallof the orbits, separate from the orbital fissure. Theseforamina are confluent with the orbital fissure in manysharks.

Supraorbital crest: On the neurocranium, an archedhorizontal plate of cartilage forming the dorsal edge of theorbit on each side; it arises from the medial orbital wall andthe cranial roof and extends horizontally from the preorbitalprocess to the postorbital process. It is apparently primitivefor shark-like fishes but is variably reduced or absent insome living elasmobranchs.

Supraorbital or brow ridge: A dermal ridge above eacheye, particularly well-developed in heterodontoids and someorectoloboids.

Symphyseal or symphysial groove: A longitudinal grooveon the ventral surface of the lower jaw of some orectoloboidsharks, extending posteriorly from the lower symphysis.

Symphysial teeth: Larger oral teeth in one row on eitherside of the symphysis, distal to medials or alternates wherepresent. Symphysials are broader than medials and usuallyhave asymmetrical roots.

Symphysis: The midline of the upper and lower jaws, wherethe paired jaw cartilages articulate with each other.

Syntype: Two or more specimens used and mentioned inan original description of a species, where there was nodesignation of a holotype or a holotype and paratype(s) bythe describer of the species.

Systematics: Scientific study of the kinds and diversity oforganisms, including relationships between them.

Tail: That part of a cartilaginous fish from the cloacalopening or vent (anus in chimaeroids, which lack a cloaca)to the tip of the caudal fin or caudal filament, and includingthe anal fin, usually the second dorsal fin when present, andcaudal fin.

Taxon, plural taxa: A taxonomic group at any level in aclassification. Thus the taxon Chondrichthyes is a class withtwo taxa as subclasses, Elasmobranchii and Holocephali,and the taxon Galeorhinus, a genus, has one taxon as aspecies, G. galeus.

Taxonomy: Often used as a synonym of systematics orclassification, but narrowed by some researchers to thetheoretical study of the principles of classification.

Term foetus: See foetus.

Terminal 3 cartilage: A wedge-shaped or elongatedcartilage articulating with the posterior edge of the ventralmarginal cartilage and over the ventral terminal cartilages. Itsupports a variety of structures, including clasper spinesand spurs, the shields of many skates (Rajoidei), and themesorhipidion of some carcharhinoid sharks.

Terminal lobe: In the caudal fin of most nonbatoid sharksand at least one batoid, the free rear wedge-shaped lobe atthe tip of the caudal fin, extending from the subterminalnotch to the posterior tip.



Terminal margin: In the caudal fin, the margin from theventral end of the subterminal margin to the posterior tip.

Terminal mouth: Mouth located at the very front of theanimal. Most cartilaginous fishes have subterminal mouths,but some species (viper sharks, wobbegongs, angel sharks,frilled sharks, whale sharks, megamouth sharks, andManta) have it terminal or nearly so.

Thorn: In many batoids, most angel sharks and the brambleshark (Echinorhinus brucus), enlarged, flat conicaldenticles with a sharp, erect crown and a flattened base(which may grow as the shark grows).

Tongue arch: See hyoid arch.

Transverse groove: In oral teeth, a deep groove transverseon the lingual root surface, transecting it into mesial anddistal root lobes.

Transverse notch: In oral teeth, a distinct notch in theproximal labial edge of the root at about its midlength.

Transverse ridges: Small narrow ridges on the labial andlingual surfaces of the crown, apicobasally oriented andsometimes extending to the cusp edges.

Tribasal pectoral fin: A pectoral fin skeleton with threebasal cartilages, the propterygium, mesopterygium, andmetapterygium, primitively found in most euselachiansincluding living neoselachians.

Trilobate lower lip: In advanced orectoloboids, shalloworolabial grooves divide the lower lips into a medial sectionand a pair of lateral sections.

Tropeic folds: Longitudinal paired ridges on the ventralmidl ine of the abdomen in fr i l led sharks(Chlamydoselachidae).

Truncate: Blunt, abbreviated.

Trunk: That part of a cartilaginous fish between its head andtail, from the last gill openings to the vent, including theabdomen, back, pectoral and pelvic fins, and often the firstdorsal fin.

Umbilical cord: A modified yolk stalk in placental viviparoussharks, carrying nutrients from the placenta to the foetus.

Unpaired fins: The dorsal, anal, and caudal fins.

Upper eyelid: The dorsal half of the eyelid, separated by adeep pocket (conjunctival fornix) from the eyeball. Theupper eyelid fuses with the eyeball and the pocket is lost inall batoids.

Upper origin: In the caudal fin, the anterodorsal beginningof the epaxial or upper web of the caudal fin, at the posteriorend of the dorso-caudal space (see measurementillustrations).

Upper postventral margin: In the caudal fin, the upper partof the postventral margin of the hypaxial web, from theposterior notch to the subterminal notch.

Uterine cannibalism or cannibal viviparity: A mode ofreproduction in which foetuses deplete their yolk-sacks earlyand subsist by eating nutritive eggs produced by the mother

(see oophagy) or first eat smaller siblings and then nutritiveeggs (see adelphophagy).

Vent: The opening of the cloaca on the ventral surface of thebody between the inner margins and at the level of the pelvicfin insertions.

Ventral: Downward, in the vertical direction of the abdomen.See dorsal.

Ventral fin: See pelvic fin.

Ventral lobe: In the caudal fin, the expanded distal end ofthe preventral and lower postventral margins, defined by theposterior notch of the caudal fin.

Ventral margin: In the caudal fin, the entire ventral marginfrom lower origin to posterior tip, either a continuous marginor variably subdivided into preventral, postventral,subterminal and terminal margins.

Ventral marginal: In the clasper skeleton, a flatsemicylindrical cartilage that is partially fused to the lateraledge of the axial cartilage, and forms the lateral wall of theclasper groove.

Ventral terminal: On the skeleton of the clasper glans, anoften triangular, elongated, curved, plate-like cartilage thatarticulates or is attached to the lateral or ventrolateral edgeof the end-style and to the posterior end of the ventralmarginal cartilage.

Ventral tip: In the caudal fin, the ventral apex of the caudalfin where the preventral and postventral margins merge.

Vertebra, plural vertebrae: A single unit of the vertebralcolumn, including a vertebral centrum and associatedcartilages that form neural arches and ribs or haemalarches.

Vertebral axis: That part of the vertebral column inside thebase of the caudal fin.

Vertebral column: The entire set or string of vertebrae or‘backbone’ of a shark, from the rear of the chondrocraniumto the end of the caudal base. Living elasmobranchs rangefrom having as few as 60 vertebrae (some squaloids of thefamily Dalatiidae) to as many as 477 vertebrae (threshersharks).

Visceral arches: See splanchnocranium.

Viviparity: Used in two ways in recent literature, as beingequivalent to placental viviparity only, that is forcarcharhinoid sharks with a yolk-sac placenta; or for allforms of live-bearing or aplacental viviparity.

Web, fin: See fin web.

Yolk sac or yolk sack: Almost all sharks start embryonicdevelopment somewhat like a chicken, as a large sphericalyolky egg inside an elongated shell, the egg case. A smalldisk of dividing cells represents the pre-embryo or blastulaatop the huge yolk mass. The blastula expands around thesides and ventral surface of the yolk mass, and differentiatesinto an increasingly shark-like embryo, the yolk sac orbag-like structure containing the yolk, and a narrow tubularyolk stalk, between the abdomen of the embryo and the yolksac.

Yolk stalk: The connecting passage between embryo orfoetus and yolk sac, which allows yolk to pass from the sacinto the embryonic gut.

Yolk-sac placenta: An organ in the uterus of some groundsharks (order Carcharhiniformes), formed from theembryonic yolk-sac of the embryo and maternal uterinelining, through which maternal nutriment is passed to theembryo. It is analogous to the placenta of live-bearing

mammals. There are several forms of yolk-sac placentas incarcharhinoid sharks, including entire, discoidal, globular,and columnar placentas (see Compagno, 1988).

Yolk-sac viviparity: Live-bearing in which the young arenourished primarily by the yolk in the yolk sacs, which isgradually depleted and the yolk sacs reabsorbed until theyoung are ready to be born.


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