Mollusks Kingdom Animalia, Phylum Mollusca (means “soft”)

What is a Mollusk? ● Mollusks are extremely diverse! ● Soft body with internal or external shell ● Ex: snails, slugs, clams, squids, and octopi ● Trochophore larva

●Bilaterally symmetrical. ● Has a nervous system with a circum- oesophagal ring, ganglia and paired nerve chords. ● Has an open circulatory system with a heart and an aorta.

● Has gaseous exchange organs called ctenidial gills. ● Reproduce sexually

●Feed a wide range of material. ●Live in most environments. ●Despite their amazing diversity, all mollusks share some unique characteristics that define their body plan

● Body plan: ● Foot – takes on many forms ● Mantle – covers the body ● Shell – (present in most) ● Visceral mass – internal organs

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Groups of Mollusks Three major classes of mollusks Gastropods Bivalves Cephalopods

Gastropod ● snails, slugs, and nudibranchs ● Shell-less or single shelled ● Move by a muscular foot ● Some are poisonous, bright colors

Snail

Spiral Mouth (radula)

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Slug

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Nudibranchs (sea slugs) Check out the nudibranch gallery at nationalgeographicnudibranch gallery at nationalgeographic

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Bivalves (things with 2 shells) Such as clams, mussels, oysters, and scallops. Bivalves are found in both freshwater and marine environments.

●Burrowing Clam: PUj1ys PUj1ys ●Ask an Expert: mussels h_ML4M h_ML4M ●Pearls: AbUf74 AbUf74

Cephalopods ● octopi, squids, cuttlefish, and nautilus ● soft-bodied, head is attached to foot ● foot is divided into tentacles with sucking disks ● small internal shells or no shell at all ● Many release ink ● Well developed eyes ● most complex of the mollusks

Octopus (creeps on tentacles)

Octopus ●Active Predators ●Learn easily, including learning by observation of another octopus ●Problem solvers

Octopus ●Fast swimmers, they can jet forward by expelling water through their mantles. And their soft bodies, with no internal or external skeleton, can squeeze into impossibly small cracks and crevices where predators can't follow. ●The amazing mimic octopuses are capable of changing their color body shape to mimic other animals

Octopus ●Have beaklike jaws that can deliver a nasty bite, and venomous saliva, used mainly for subduing prey. ●They have been found to play with “toys” and have personalities ●They have blue blood!!

Intro: Octopus versus Shark: Octopus escapes jar: Octopus camouflage: Octopus Houdini:

Cuttlefish (the chameleon of the sea)

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● Nautilus is only cephalopod with shell ● Squid have a modified shell called a pen ● Like the octopus, squids also have parrot- like beaks

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Squid

●Giant Squid Documentary: pZ1PIE pZ1PIE

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