• Shell of CaCO3
• Shell secreted by mantle
• Visceral mass
• Muscular foot
• Radula

• Nacre--Irridescent first layer

• Pearl--Made from nacre layer

Molluscs have...

• Open circulation
• Pumping heart and vessels
• Reduced coelum--hemocoel
• Hemolymph--blood
• Metanephridia
• Trochophore larval stage
• Share ancestor with Annelids

Class Polyplacophora

Chitons

• Flattened dorsoventrally
• 8 interlocking plates
• Found in rocky intertidal zones
• Broad foot
• Mantle wraps around plates
• Radula
• External gills

Class Gastropoda

Snail, Slugs, etc.

• 2nd largest class in the Animal Kingdom
• Mostly marine, some land--pulmonate
• Coiled shell except limpets and nudibranchs
• Torsion--twisting of visceral mass when the snail is an embryo, anus over head.

Class Bivalvia

Clams, Oysters, etc.

• Two part shell 
• No head
• Sedentary or sessile
• No radula--filter feeders

Class Bivalvia

Anatomy

• Dor/Ven/Ant/Pos
• Umbo--starts shell growth, on Ant. side
• Foot
• Siphons--Excurrent above incurrent
• Ciliated gills
• Adductor muscles

Class Bivalvia

Diversity--Eastern Oysters

• Important to Chesapeake Bay
• Sessile
• Overharvesting and disease have declined the population
• Dioecious
• Spawn in spring--trochophore-->veliger larva-->spat-->adult

Class Bivalvia

Diversity--FW bivalves

• No planktonic larval stage
• Internal fertilization
• Glochidia(um)--fish gill parasite

Class Bivalvia

Diversity--Zebra Mussels

• FW
• Introduced spp
• Found in Great Lakes
• Clog pipes
• Planktonic larval stage 

Class Bivalvia

Diversity--Shipworms

• Grows into adult while feeding
• Burrows in wood

Class Bivalvia

Diversity--Scallops

• Eyes or light detectors
• Can swim

Class Bivalvia

Diversity--Tridacnid clams

• Zooxanthellae in mantle
• Light detectors

• 1 plate
• No hinge
• Symmetrical
• Thought extinct but found recently
• Known for repitition of structures

• Tusk like shells
• Open at both ends
• Deposit feeders
• Live in intertidal zone

Class Cephalopoda

Squids, Octopi, Nautiluses

• "Head-foot"
• Octopus--8 arms, no tentacles
• Squiid--8 arms, 2 tentacles
• Nautilus--90+ arms

Class Cephalopoda

Locomotion

• Jet propulsion--force water through funnel
• Fins--stabalize squid and nautilus
• Octopus uses arms to crawl

Class Cephalopoda

Shell

• Nautilus--chambered shell for buoyancy
• Cuttlefish--internal shell "cuttlebone"
• Squid--thin proteinacious strip "pen"
• Octopus--no shell

Class Cephalopoda

Subclasses

• Ammonoids--extinct, coiled chambered shell

• Nautiloids--mostly extinct, only extant spp is Nautilus

• Coeloids--all extant spp

Class Cephalopoda

Architeuthis

• Giant Squid
• Largest invertebrate known 

Class Cehpalopoda

Vampiroteuthis

• Vampire squid
• Actually an octopus
• Arms with hooks
• Large eyes

Class Cephalopoda

Advancement

• Largest invertebrate brain
• Giant nerve fibers
• Communicate through movement and chromatophores
• Light organs give extreme control over color and texture of organism

Class Cephalopoda

Feeding and Reproduction

• Feeding--beak, arms, suckers, teeth, radula, venom

• Reproduction--courtship, male transfers sperm sac (spermatophore) to female using a special arm (hectocotylus)