1 phylum mollusca bio 2215 oklahoma city community college dennis anderson
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Phylum Mollusca
BIO 2215
Oklahoma City Community College
Dennis Anderson
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Phylum Mollusca
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Numbers of speciesNumbers of species
Echinodermata
Ciliophora
Chordata
Mollusca
Platyhelminthes
Nematoda
PoriferaAnnelida
Other
Apicomplex
Sarcomastigophora
Arthropoda
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Molluscs
• 50,000 -100,000 living species
• 35,000 extinct species• Largest = 1000 pounds• 80% less than 5 cm• Soft body• Most have a shell• Most marine• Snails terrestrial
– Most habitat
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Phylum Mollusca
• Ventral Foot– Locomotion
• Mantle– Encloses mantle cavity
• Shell• Radula• Coelom
(eucoelomate)• Metanephridia• Open circulatory
system– Closed in cephalopods
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Economics
• Pearls• Burrowing shipworms • Snails & slugs
– Garden pests– Food– Intermediate hosts for
parasites
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Trochophore Larva• Same type as Phylum
Annelida
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MyxozoaMyxozoa
ArthropodaArthropoda AnnelidaAnnelida
MolluscaMollusca
LophophoresLophophores
HemichordataHemichordata
VertebrataVertebrata
Other pseudocoelomates
Other pseudocoelomates
NematodaNematoda
PoriferaPorifera
CtenophoraCtenophoraCnidariaCnidaria
PlacozoaPlacozoa
PlatyhelminthesPlatyhelminthes
NemerteaNemertea
CiliophoraCiliophoraSarcomastigophoraSarcomastigophora
MicrosporaMicrosporaApicomplexaApicomplexa
MesozoaMesozoa
EchinodermataEchinodermata
CrustaceaCrustaceaChelicerataChelicerata
UniramiaUniramia
Other ChordataOther Chordata
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Generalized Mollusc
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Body PlanBody Plan
Mantle cavityMantle cavity
CtenidiumCtenidium
Pericardial cavityPericardial cavity MetanephridiumMetanephridium
RadulaRadula
GonadGonad
Stomach and digestive glandStomach and digestive gland FootFoot
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Dorsal mantle covers the visceral mass.
Dorsal mantle covers the visceral mass.
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Secretes the shellSecretes the shell
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Ctenidium (Respiration)Ctenidium (Respiration)
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Complete digestive systemComplete digestive system
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Paired ventral nerve cordsPaired ventral nerve cords
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RadulaRadula
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Source: From A Life of Invertebrates, Copyright © 1979 W. D. Russell-Hunter.
Radular Structure
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Coelom - metanephridiaCoelom - metanephridia
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Class PolyplacophoraChitons
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Class PolyplacophoraClass Polyplacophora
• Eight dorsal plates• Reduced head• Radula reinforced
with iron– Scrape algae from
rocks
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Class Polyplacophora
Mantle cavityMantle cavityMouthMouth
CtenidiumCtenidium
FootFoot
AnusAnus
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Class PolyplacophoraClass Polyplacophora
MouthMouth
Digestivegland
Digestivegland
StomachStomach GonadGonadPericardial cavityPericardial cavity
NephridiumNephridium
AnusAnus
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Class BivalviaClams, Oysters, Shipworms
Class BivalviaClams, Oysters, Shipworms
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Class Bivalvia
• Two shells• Most are filter feeders• No head or radula• Burrow
– Sand, wood, rocks
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Giant Clam & Burrowing Clam
Siphon
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Zebra Mussel
• Environmental Pest• Ballast water of ships
from Europe in 1986• Attack be secreting
adhesive byssal threads– Each other– Other mussels– Man made objects
• Pipes, plumbing
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Zebra Mussel
• Live in high densities• Feed on
phytoplankton• Reproduce rapidly
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Zebra Mussel
• Attach to native mussels
• Killed all native mussels in Lake Erie
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Distribution of Zebra Mussel
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Bivalve structuresBivalve structures
IncurrentsiphonIncurrentsiphon
CtenidiumCtenidium
ExcurrentsiphonExcurrentsiphon
HingeHinge
FootFoot
Labial palpLabial palp
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Clam anatomyClam anatomyPericardial cavityPericardial cavity
HeartHeart
GonadGonadIntestineIntestine
StomachStomach IncurrentIncurrent
ExcurrentExcurrent
IntestineIntestine
MetanephridiumMetanephridium
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Clam anatomyClam anatomy
GonadGonadIntestineIntestine
StomachStomachIncurrentIncurrent
ExcurrentExcurrent
Digestivegland
Digestivegland
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Clam anatomyClam anatomyPericardial cavityPericardial cavity
HeartHeart
IncurrentIncurrent
ExcurrentExcurrent
IntestineIntestine
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Clam anatomyClam anatomyPericardial cavityPericardial cavity
HeartHeart
GonadGonad
IncurrentIncurrent
ExcurrentExcurrent
IntestineIntestine
MetanephridiumMetanephridium
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Oysters
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Pearl formation
Developing pearlDeveloping pearl
EpitheliumEpithelium
ShellShell
Irritant lodged between shell and mantle
Layers of nacre secreted around foreign material
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Scallops
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Shipworms
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Class GastropodaSnails, Slugs, Conchs, Limpets
Class GastropodaSnails, Slugs, Conchs, Limpets
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Class Gastropoda
• One shell (if present)• Torsion of body
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Snail
• Terrestrail• Mantle cavity
functions as lung
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Snail
Tentacle(Eye stalks)Tentacle(Eye stalks)
TentacleTentacle
PneumostomePneumostome
AnusAnus
FootFootMouthMouth
Genital poreGenital pore
ShellShell
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Internal Structure of a Generalized Gastropod
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Nudibranch
• No shell• Dorsal projections
– Gills– Nematocyst discharge
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AbaloneAbalone
• Several holes in top of shell– Excrete waste
• Food for man
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Slug
• No shell• Garden pests
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Limpet
• Herbivores• Cling to rocks or other surfaces
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Conch
• Large shell• Marine• Many are predators
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Class CephalopodaSquids, Octopuses, Nautiluses
Class CephalopodaSquids, Octopuses, Nautiluses
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Class Cephalopoda
• Shell in squid and octopus absent or vestigial
• Jet propulsion• Ink sac• Foot modified into
arms and tentacles• Marine• All predators
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SquidSquid
DorsalVentral
Posterior surface
Right
Left
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SquidSquid
FinFin
ArmArm
Funnel (siphon)Funnel (siphon)
EyeEye
TentacleTentacle
CollarCollar
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SquidSquidShell (Pen)Shell (Pen)
CtenidiumCtenidium
FunnelFunnel
SystemicheartSystemicheart
Branchial heartBranchial heart
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Squid MaleSquid MaleTestisTestis
Hectocotylous armHectocotylous arm
PenisPenis
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Squid FemaleSquid Female
Ovary with eggsOvary with eggs
Nidamental glandsNidamental glands
Oviducal glandOviducal gland
Oviducal openingOviducal opening
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Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cephalopod Eye
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Octopus
• Eight arms with suckers
• Crawl or eject water from siphon
• Change skin color– chromatophores
• Most intelligent invertebrate
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Nautilus
• Up to 94 tentacles– No suckers
• Shell with many chambers– Lives in outermost
chamber
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Ammonoids
• Extinct• Devonian to
Cretaceous– 400 to 65 MYA
• Died out with dinosaurs
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Class Scaphopoda
• Tooth shells• Shell opens on both
ends• Burrow into mud• No gills
– Mantle for gas exchange
• Feed on detritus and protozoa
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Class ScaphododaClass Scaphododa
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The End
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