Phylum: Mollusca

Common Names:

Class Polyplacophora: Chitons

Class Gastropoda: Snails and Slugs

Subclass Prosobranchia: Sea snails, Land Snails, Freshwater Snails

Subclass Opisthobranchia: Sea Slugs, Sea Hares

Subclass Pulmonata: Air Breathing Snails and Slugs

Class Bivalvia: Clams, Oysters, Mussels, Scallops

Class Cephalopoda: Squid, Octopus, and Cuttlefish


Identity of Mollusc Shells

Class: Bivalvia


Class: Gastropoda/Prosobranchia


Class: Prosobranchia

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Class: Polyplacophora


Class: Chiton


External Anatomy:


Live Gastropods

Class Gastropoda/ Subclass: Opisthobranchia/ Sea Slug


Locomotion: Sea slugs use their muscular foot for crawling around. Their foot secretes a mucus. They slide along their mucus beating their cilia to move.

Class: Bivalvia/ Scallop With Mussel Attached



Locomotion: Scallops use jet propulsion by closing both sides of their shells with the adductor muscle. They are able to move vertically and horizontally.

Class: Gastropoda/ Subclass: Prosobranchia/ Whelk


Locomotion: Their muscular foot helps them glide along or just beneath the sand on the ocean floor

Class: Gastropoda/ Subclass: Prosobranchia/ Sea Snail



Locomotion: Use their foot to float or swim in the water

Class Bivalvia/ Clam


Screen Shot 2017-12-02 at 7.51.31 PM.png

Locomotion: Their foot comes out of the shell and digs in the sand and contracts which pulls the clam forward

Clam Dissection/ Anatomical structures identified above


 Suspension Feeding in a Bivalve:

Bivalves feed on material (such as planktonic organisms) suspended in water and has various structural modifications such as trapping by mucous and trapping without the use of mucous. For straining out its food. Water currents to bring particles to the Bivalve.

Bivalve Reproduction:

Some Bivalves reproduce by externally fertilizing. They release sperm into the water, where they either meet eggs that have also been released or are sucked in to fertilize eggs within another bivalve.

Class Bivalvia/ Mussel


Locomotion: There are swimming and completly sessile mussels. They have got a byssus gland at their foot’s end, producing a thread that hardens in water and can be used to fasten the mussel to the ground. Later the thread can be severed (Mytilus) or thrown off (Pinctada).


Mussel Gills/Image Mag: 4x


Snail Radula/Image Mag: 4x


Clam/ Image Mag: 4x


Squid Dissection

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Features/Characteristics of Molluscs

Octopus: Vary from 3 inches to 30 feet. Eight lets covered with suckers. Their bodies consist of 90 percent muscle and have no internal or external skeleton. Keen nest builders and can live in lots of habitats such as tropical, pacific and Atlantic waters. They have a hard beak which they use to bite and kill their prey. Carnivores and typically do their hunting at night. Shorter lifespans, around 6 months but some species can live up to 5 years. As an adaptation, they have a special pigment int heir skin which allows them to camouflage and blend in with their environment. They also have dark in that shoots out of their bodies and confuses predators.

Squid: Squids live usually in deep oceanic habitats. They have bilateral symmetry, a mantle, eight arms, and two tentacles. They use gills for breathing and swimming and chromatopheres, which give squid the ability to change color and adapt to its environment allowing it to camouflage. They also have blank ink. When attacked squid will use their tentacles to wrap around its prey in an attempt to protect itself and stay away from its predators mouth.

Cuttlefish: One of the most intelligent inverts in the world. They internally produced ink and also has a neuro-toxin that can be used on prey. Because of their distinct ‘w’ shaped pupil. The unique formation of the pupil provides the Cuttlefish with a very well developed sight that focus’s on contrast rather than color which works especially well in their dark underwater environment. Also camouflage and can even influence the color of light reflected from its skin and even the polarization of light which can be used to signal others.

Nautilus: They have an external shell and as the animal grows, its body moves forward and a wall called a septum is produced that seals off the older chambers. The body is contained in the last compartment—the newest and largest of them all. The animal can completely withdraw its body into its shell, closing the opening with a leathery hood. A nautilus does not have suckers on its tentacles like an octopus does. Instead its tentacles are lined with alternating grooves and ridges that allows it to grip objects.

How Nautilus Regulate Buoyancy: Nautilus regulates their buoyancy by adding or removing water and gas from the chambers of its shell.




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