Mollusks are a diverse phylum with over 50,000 species across 10 classes. They include squid, octopus, clams, snails, and oysters. Mollusks have a mantle, foot, and radula as basic anatomical structures. The foot is adapted for movement and the mantle circulates water and secretes shells. Gastropoda includes snails and slugs with a radula and sometimes a shell. Bivalvia includes clams and oysters with two hinged shells and siphons. Cephalopoda are advanced mollusks like squid and octopus with specialized features for swimming including fins or jet propulsion.

1. MollusksKingdom AnimaliaPhylum Mollusca Class Gastropoda Class Bivalvia Class Cephlapoda

2. Mollusks50,000 species10 classesIncludes:SquidOctopusClamsConchesSnailsSea slugsOysters

3. Basic Anatomical Structures:a) Mantle – muscular bag that surrounds the gills and most organs and is used to circulate water1. some use it to circulate water or jet propulsion2. secretes calcium carbonate shell

4. Basic Anatomical Structures:b) Foot – muscular structure used for movement 1. In snails & slugs it’s used to crawl 2. In bivalves it’s used to dig 3. In squids, it takes the form of tentacles

5. Basic Anatomical Structures:c) Radula – a tongue like structure with scraping teeth

6. Class GastropodaIncludes snails, slugs, whelks, & abaloneDefining Characteristics:Radula

7. Some have a shell

8. Sensitive Tentacles

9. Shell-less members can produce toxins or store eaten nematocysts

10. Snails Sea SlugsWhelks Abalone

11. Class Bivalvia:Includes clams, oysters, mussels, scallopsDefining characteristics:Two hinged shells

12. No head, but sensory organs on shells edge

13. Two siphons extend out of the shell

14. Mantle pumps water

15. Clam OysterMussel Scallop

16. Clam OysterMussel Scallop

17. Pearl Making AbilitiesWhen ever sand or an irritant gets inside a shell of an oyster, it coats it in a substance called nacre, creating a pearlPearl farmers put seeds inside oysters to create pearls

18. Class CephalopodaIncludes squid, octopus, nautilus, cuttlefishDefining Characteristics:Little to no shell, ranging from gastropod like shell (nautilus) to internal leaf like shell (cuttlefish) to thin internal bar called a pen (squid) to nothing (octopus)Class CephalopodaDefining Characteristics:Specialized foot called a siphon for jet propulsion

19. Ink sac

20. Chromatophores – cells that can change color

21. Complex nervous systems consisting of large eyes and critical thinking abilitiesOctopus8 arms

22. Beak like jaws

23. No shell

24. Bottom dwellersSquidBetter adapted for swimming due to elongated body and two fins formed by the mantle

25. Ten arms, two of which are longer are called tentacles

26. A reduced shell called the pen can be found embedded in the upper surfaceCuttlefishResemble squids

27. Eight arms and two tentacles

28. Flattened with a fin along the sides

29. Internal ShellNautilusSmooth exterior shell

30. Contains several gas filled chambers that aid in buoyancy

31. Has 60-90 arms to catch prey