2. Mollusc Characteristics
Unsegmented soft body
Visceral mass
Molluscs have a Modified Foot
Muscular foot and/or tentacles
Have a mantle (fold in the body wall that lines the shell)
Most have shell (internal or external)
Or remnants of a shell
Pen in squid

3. Tentacles/ modified foot
Mantle
foot
Shell
head
Mantle
cavity

4. Classes of Molluscs • Class Cephalopoda – octopus and squid
There are 8 classes of molluscs but this course will look at the 3 main classes.
• Class Cephalopoda –
octopus and squid
• Class Gastropoda –
slugs and snails
• Class Bivalvia – clams,
mussels, scallops

6. Class Gastropoda • free-living; marine, terrestrial, fresh water
• noticeable head
• single shell, often spiral
• muscular foot is attached near the stomach area

10. Class Bivalvia • marine and freshwater • gill used for gas exchange
• all are sessile, suspension feeders and filter food from the water
• all have two part shells
(bivalves)

12. A giant clam can be 4 to 6 feet in diameter!

13. Other Bivalves
The bivalves are the second largest class of molluscs. They differ from snails in having two shells, usually mirror images of each other. Some like oysters and mussels live attached to rocks and other hard surfaces while others, like pipis, burrow in sand. Leptonoidean bivalves (in picture) are a group which usually live commensally with other animals. Most have a large foot and are active crawlers (1mm).
Limatula strangei. Some bivalves, such as the scallops are able to actively move when endangered by vigorously flapping their shells and squirting out jets of water. Limatula also moves very vigorously when disturbed. The tentacles around the mantle edge are sticky, very mobile and parts can break off them when the animal is disturbed, leaving a potential predator with a sticky writhing worm-like object to deal with as the Limatula escapes (25mm).

14. Scallop with a “buddy” on top!

15. Bay Scallop before cooking
Inside of Bay Scallop

16. Cooked scallops! YUMMY!

17. Class Cephalopoda • Exclusively marine
Shell- “pen”- internal remnant of a shell
Use fins and siphon to move
Modified foot= tentacles
• Fast swimming predators
-use tentacles to catch prey
• Have a special camera like eye
Ex- Giant Squid

18. Squid External Anatomy
Fins
Mantle
Siphon

19. Squid Internal Anatomy

20. Squid swimming with Mrs
Squid swimming with Mrs. Ross while scuba diving off the coast of Jamaica

21. Can you see the squid?

22. Do you think these squid are related?

25. BEFORE….

26. AFTER!

29. So, when do I get to see you and your relatives photos?