Chapter 31 - Protostome Animals - 31.2 - Many Laphotrochozoans - 31.2 Recap - Learning Outcomes - Page 671: 3

All mollusks have three main body parts: a mantle, the visceral mass, and the foot. The mantle is responsible for producing an exterior shell (or interior, in the case of most cephalopods). The visceral mass is the body of the mollusk and contains the organs. The foot is used for locomotion. Mollusks such as bivalvia have developed two shells instead of one for more thorough protection. The mantle of cephalopods such as squids and octopi secrete a softer interior shell to boost the animal's speed through water.

All mollusks have three main body parts: a mantle, the visceral mass, and the foot. The mantle is responsible for producing an exterior shell (or interior, in the case of most cephalopods). The visceral mass is the body of the mollusk and contains the organs. The foot is used for locomotion. Mollusks such as bivalvia have developed two shells instead of one for more thorough protection. The mantle of cephalopods such as squids and octopi secrete a softer interior shell to boost the animal's speed through water.