Phylum Mollusca

1. Phylum Mollusca • The mollusks are invertebrate animals known as Mollusca. • There are more than 150,000 species within this phylum.

2. Types of Molluscs • snails • clams • squid • cuttlefish • octopus which are among the most neurologically-advanced invertebrates

3. Commercial Use • There are a wide variety of molluscs valued by humans as seafood or for their decorative shells. • The edible species include many kinds of clams, snails, squid and octopuses.

4. Mollusca octopus • Order Octopoda have venon glands in their beaks

5. Classes of Mollusks • Class: Gastropoda • Class: Bivalvia 3) Class: Cephalopoda 4) Class: Polyplacophora

6. Characteristics of Mollusks • soft-bodied animals that includes: snails, clams, and sea slugs. • The most common characteristic of most mollusks is their shell. Snails are univalves, which means they have one shell. • The bivalves, or two-shell, mollusks include the clams, scallops, and oysters, the oyster produces the pearl. • Some mollusks have lost their shells altogether. The octopus, the squid, and the sea slugs have evolved their own survival strategies to replace their protective armor • It is due to the absence of a protective shell the octopus has evolved the largest and most complex brain of all the mollusks

7. Characteristics continued • All members of mollusks have a muscular bag surrounding the gills and organs called the mantle • Most mollusks have a muscular foot(squid have tentacles) • Mollusks haveradula(teeth used for scraping/feeding) • Mollusks develop as a trochophore and then into a veliger

8. gastropods are common in both salt and fresh water and on land.  Class Gastropoda Class Gastropoda

9. Triton shell

10. Nudibranch

11. Nudibranch

12. Nudibranch

13. snails, whelks, periwinkles, abalone, and slugs, are the largest group of mollusks Garden slug periwinkle snail abalone

16. Class Bivalvia • bivalves include clams, oysters, scallops, and mussels  • they have two parts, or valves, into which the shell is divided.  One or two large, well-developed adductor muscles (the edible part) are used to close the shell • Bivalves lack defined heads • they also have no radula. A foot is present but laterally compressed • Bivalves generally have a large mantle cavity with gills • the edges of the mantle may be fused to form siphons that circulate water to and from the gill chamber.

17. Scallop

18. Left and Right Sides

21. Class Cephalopoda • The cephalopods (the “head-foots”) • the most evolutionarily advanced animals to be found among the invertebrates.  • strictly marine class

22. Reef Squid

23. Cuttlefish

24. Blue-ring octopus

25. Chambered nautilus

26. Class Polyplacophora • Chitons are primitive marine mollusks. • Chitons have a shell that is made of eight separate shell plates. The plates provide protection, allow the chiton to flex upward when needed for movement, and to curl up into a ball. • The shell plates are surrounded by a structure known as a girdle.

27. Chiton

28. Chiton

29. Brachipod Phylum Brachiopoda