about hyena

7/29/2019 About Hyena

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ENGLISH

SNAMA : KADEK RAY

KELAS : XI IA 2

SENIOR HIGH SCHOOL 4 KENDARI


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HYENA


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Hyena

Hyenas (from Greek "" - huaina) are theanimals of the family Hyaenidae,a feliform suborder of the Carnivora. It is the

smallest biological family in the Carnivora(consisting of four species), and one of thesmallest in the mammalia. Despite their lowdiversity, hyenas are unique and vital

components to most African andsome Asian ecosystems.


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Although phylogenetically close

to felines and viverrids, hyenas are behaviourally

and morphologically similar to canines in severalaspects (see Convergent evolution) ; both hyenas

and canines are non-arboreal, cursorial hunters

which catch prey with their teeth rather than their

claws. Both eat their food quickly and may store it,

and their calloused feet with large, blunt, non-

retractible nails are made for running and making

sharp turns. However, the hyenas' grooming, scentmarking, defecating habits, mating and parental

behaviour are consistent with the behaviour of

other feliforms.


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Although long reputed to be cowardly

scavengers, hyenas, especially spotted hyenas,

do occasionally hunt for themselves, and have

been known to drive off leopards or lionesses

from their kills. Hyenas are primarily nocturnalanimals, but may venture from their lairs in the

early morning hours. With the exception of the

highly social spotted hyena, hyenas are generallynot gregarious animals, though they may live in

family groups and congregate at kills.


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Hyenas first arose in Eurasia during the Miocene period

from viverrid-like ancestors, and developed into two

distinct branches ; the lightly built dog-like hyenas andthe robust bone-crushing hyenas. Although the dog-like

hyenas thrived 15 million years ago (with

one taxon having colonised North America), they died

out after a change in climate along with the arrival

of canids into Eurasia. Of the dog-like hyena lineage,

only the insectivorous aardwolf survived, while the

bone-crushing hyenas (whose extant members arethe spotted, brown and striped hyena) became the

undisputed top scavengers of Eurasia and Africa.


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Hyenas feature prominently in the folklore and

mythology of human cultures they are sympatric

with. Hyenas are mostly viewed with fear and

contempt, as well as being associated with

witchcraft, as their body parts are used as

ingredients in traditional medicine. Among the

beliefs held by some cultures, hyenas are

thought to influence peoples spirits, rob graves,and steal livestock and children


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OriginsHyenas originated in the jungles of Miocene Eurasia 22

million years ago, when most early feliform species

were still largely arboreal. The first ancestral hyenas

were likely similar to the modern banded palm civet ;

one of the earliest hyena speciesexhumed, Plioviverrops was a lithe, civet-like animal

which inhabited Eurasia 20-22 millions years ago, and is

identifiable as a hyaenid by the structure of the middle

ear and dentition. The lineageof Plioviverrops prospered, and gave rise to

descendants with longer legs and more pointed jaws, a

direction similar to that taken by canids in North

America.


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Skull ofIctitherium viverrinum, one of the "dog-like"hyenas. American Museum of Natural History
http://en.wikipedia.org/wiki/File:Ictitherium_viverrinum.JPG


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Rise and fall of the

dog-like hyenas

The descendants

ofPlioviverrops reached their

peak 15 million years ago,with more than 30 species

having been identified.

Unlike most modern hyena

species which are specialisedbone-crushers, these dog-like

hyenas were nimble-bodied,

wolfish animals; one speciesamong them

as Ictitherium viverrinum,

which was similar to a jackal.
http://en.wikipedia.org/wiki/File:Stripedspottedhyenas.jpg


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The dog-like hyenas were very numerous; in some

Miocene fossil sites, the remains ofIctitherium and other

dog-like hyenas outnumber those of all other carnivores

combined. The decline of the dog-like hyenas began 5-7

million years ago during a period of climate change,

which was exacerbated when canids crossed the Bering

land bridge to Eurasia. One species, Chasmaporthetes

ossifragus, managed to cross the land bridge into North

America, being the only hyena to do

so. Chasmopothertes managed to survive for some time

in North America by deviating from the cursorial andbone-crushing niches monopolised by canids, and

developing into a cheetah-like sprinter. The dog-like

hyenas died off 1.5 million years ago.


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Bone-crushing hyenas

By 10-12 million years ago, the hyena family hadsplit into two distinct groups ; that of the dog-likehyenas and the bone-crushing hyenas. The arrivalof the ancestral bone-crushing hyenas coincidedwith the decline of the similarly built butunrelated Percrocutidae family. The bone-crushing hyenas survived the devastating changesin climate and the arrival of canids which wipedout the dog-like hyenas, though they never

crossed into North America, as their niche therehad already been taken bythe Borophaginae family.


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By 5 million years ago, the bone-crushing hyenas

became the dominant scavengers of Eurasia,primarily feeding on large herbivore carcasses

felled by sabre-toothed cats . One

genus, Pachycrocuta, was a 200 kg (440 lb)mega-scavenger which could splinter the bones

of elephants. With the decline of large

herbivores by the late ice age, Pachycrocuta was

replaced by the smaller Crocuta.


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Rise of modern hyenas

The aardwolf can trace its lineage directly backto Plioviverrops 15 million years ago, and is theonly survivor of the dog-like hyena lineage. Itssuccess is partly attributed to its insectivorous

diet, for which it faced no competition fromcanids crossing from North America. Itsunrivaled ability to digest the terpene excretionsfrom soldiertermites is likely a modification of

the strong digestive system its ancestors used todigest foetid carrion.


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The striped hyena may have evolved from H.

namaquensis of Pliocene Africa. Striped hyena fossils are

common in Africa, with records going back as far as theMiddle Pleistocene and even to the Villafranchian. As

fossil striped hyenas are absent from

the Mediterranean region, it is likely that the species is a

relatively late invader to Eurasia, having likely spreadoutside Africa only after the extinction of spotted

hyenas in Asia at the end of the Ice Age. The striped

hyena occurred for some time in Europe during the

Pleistocene, having been particularly widespreadin France and Germany. It also occurred

in Montmaurin, Hollabrunn in Austria, the Furninha Cave

in Portugal and the Genista Caves in Gibraltar.


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The European form was similar in appearance to

modern populations, but was larger, being comparable

in size to the brown hyena.

The spotted hyena diverged from the striped and

brown hyena 10 million years ago. Its direct ancestor

was the Indian Crocuta sivalensis, which lived during

the Villafranchian. Ancestral spotted hyenas probablydeveloped social behaviours in response to increased

pressure from rivals on carcasses, thus forcing them to

operate in teams. Spotted hyenas evolved sharp

carnassials behind their crushing premolars, thereforethey did not need to wait for their prey to die, as is the

case for brown and striped hyenas, and thus became

pack hunters as well as scavengers.


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They began forming increasingly larger

territories, necessitated by the fact that their prey

was often migratory, and long chases in a smallterritory would have caused them to encroach

into another clan's turf. Spotted hyenas spread

from their original homeland during the MiddlePleistocene, and quickly colonised a very wide

area from Europe, to southern Africa

and China. With the decline of grasslands 12,500

years ago, Europe experienced a massive loss oflowland habitats favoured by spotted hyenas, and

a corresponding increase in mixed woodlands.


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Genera of the Hyaenidae (extinct and

recent)

ReconstructionofPachycrocuta breviostris

A spotted hyena of subfamilyHyaeninae
http://en.wikipedia.org/wiki/File:Crocuta_crocuta.jpghttp://en.wikipedia.org/wiki/File:Short-faced_hyena1.JPG


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Their pelage is sparse and coarse with poorly

developed or absent underfur. Most species have

a rich mane of long hair running from the withers

or from the head. With the exception of the

spotted hyena, hyaenids have striped coats which

they likely inherited from their vivverid ancestors.

Their ears are large and have simple basal ridgesand no marginal bursa. Their vertebral column,

including the cervical region are of limited

mobility. Hyenas have no baculum. Hyenas havean additional pair of ribs than canids, and their

tongues are rough like those of felids and

vivverids.


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Males in most hyena species are larger than

females, though the spotted hyena is exceptional,

as it is the female of the species that outweighsand dominates the male. Also, unlike other

hyenas, the female spotted hyena's external

genitalia closely resembles that of the male.

Their dentition is similar to that of the Felidae, but

is more specialised for consuming coarse food and

crushing bones. The carnassials, especially the

upper, are very powerful and are shifted far backto the point of exertion of peak pressure on the

jaws.


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The other teeth, save for the underdeveloped

upper molars, are powerful, with broad bases and

cutting edges. The canines are short, but thick androbust. Labiolingually, their mandibles are much

stronger at the canine teeth than in canids,

reflecting the fact that hyenas crack bones with

both their anterior dentition and premolars, unlike

canids which do so with their post-carnassial

molars. The strength of their jaws is such that both

striped and spotted hyenas have been recorded tokill dogs with a single bite to the neck without

breaking the skin.


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Hyenas lack perinial scent glands, but have a large

pouch of naked skin located at the anal opening.

Large anal glands open into it from above the anus.Several sebaceous glands are present between the

openings of the anal glands and above them. These

glands produce a white, creamy secretion which is

pasted onto grass stalks. The odour of this secretion

is very strong, smelling of boiling cheap soap or

burning, and can be detected by humans several

metres downwind. The secretions are primarilyused for territorial marking, though both the

aardwolf and the striped hyena will spray them

when attacked.


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Behaviour

Hyenas groom themselves often like felids and viverrids,and their way of licking their genitals is very cat-like(sitting on the lower back, legs spread with one legpointing vertically upward). However, unlike otherfeliforms, they do not "wash" their faces. They defecate in

the same manner as other Carnivora, though they neverraise their legs as canids do when urinating, as urinationserves no territorial function for them. Instead, hyenasmark their territories using their anal glands, a trait found

also in viverrids and mustelids, but not canids andfelids. When attacked by lions or dogs, striped and brownhyenas will feign death, though the spotted hyena willdefend itself ferociously.


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The spotted hyena is very vocal, producing a

number of different sounds consisting of whoops,

grunts, groans, lows, giggles, yells, growls, laughs and

whines. The striped hyena is comparatively silent, its

vocalisations being limited to a chattering laugh and

howling.

Mating between hyenas involves a number ofshort copulations with brief intervals, unlike with

canids in which there is a single, drawn out

copulation. Spotted hyena cubs are born almost fully

developed, with their eyes open and erupting incisorsand canines, though lacking adult markings. In

contrast, striped hyena cubs are born with adult

markings, closed eyes and small ears.

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