PHYLUM MOLLUSCA

Question 1

Where are molluscs typically found?

Answer 1

All major environment:

• marine (all classes)
• fresh water (gastropods & bivalves)
• terrestrial (gastropods)

Question 2

Describe the body plan of the phylum Mollusca.

Answer 2

Body has four largely independent regions:
- mantle (often w/ a shell)
- head
- foot
- viscera
Has 2 unique functionally important traits:
- ctenidium (gill) and radula

Question 3

Describe the mantle found in the Phylum Mollusca.

Answer 3

Tissue layer that covers most or all of the body

Question 4

How are new shells formed in molluscs?

Answer 4

The mantle adds new shell by accretionary growth at the edge of a tapered tube

Question 5

Describe the mantle cavity found in molluscs.

Answer 5

Supports many functions:
- respiration (all)
- Feeding (some)
- locomotion (some)
- brood chamber (some)
Different forms in different taxa
Has unique ciliated gill bipectinate ctenidium(one to many depending on taxon)

Question 6

What is the function of bipectinate ctenidium?

Answer 6

A unique ciliated gill that pumps water and plays an important role in suspesion feeding in some groups

Question 7

What is the function of the radula?

Answer 7

Feeding structure

Flexible ribbon studded with many rows of chitinous teeth

Question 8

Describe the two fluid-filled cavity that lie within the mesoderm.

Answer 8

Coelom: arise via schizocoely and is greatly reduced (only surrounds heart, gonad, kidney)
Hemocoel: extensive, blood is pumped by heart through vessels to spongy tissus
- fxn as circulatory system and hydraulic skeleton