Molluscs 2BIbDF09 10/11

What are molluscs?

They are animals with a bilateral symmetry and an exoskeleton called a shell. There are three different groups of molluscs; the Gastropods, the Cephalopods and the Bivalves. All of them have a body separated in three parts. First part is the foot is the strong, muscular portion used for locomotion. Second one the visceral mass is the soft-bodeid portion that contains internal organs and the thrid one the mantle is a membraous, or sometimes muscular , covering that envelops the visceral mass

Molluscs are soft-bodies animals, but most are are protected by a hard shell. Many molluscs feed by using a straplike rasping organ called a radula to scrape up food. (cf picture from Essential Biology) All of molluscs have a similar body plan.

The Gastropods

The Gastropods include the snails and the slugs. Some of them live into the water. These molluscs can be unisexual or hermaphrodite. The Gastropods meaning stomach-footed. They move by muscle contractions, thanks their foot,which its become ventrally flattened foot when they move. They can have a shell like the snails.

The Cephalopods

tantaculas, swim by jet projection energy-consuming mode of locomotion

References

• http://www.earthlife.net/inverts/mollusca.html

Essential Biology with Physiology Campbell/Reece/Simon Second Edition