Molluscs have soft, moist bodies protected by a shell. Most molluscs live in water. Slugs and snails live on land.
GROUPS OF MOLLUSCS:
Gastropods: They have a shell that they hide in when they sense danger. They have a head whith four tentacles, where their sense organs are located. Gastropods move by sliding on a slimy, mucus substances that they excrete.
Bivalves: They have one shell divided into two moving parts, called valves, which they close when they sense danger. They stay in one place. They eat small organisms that are in the water. Mussels and clams are bivalves.
Cephalopods: have no protective external covering, but some have a shell hidden under the skin. All cephalopods are marine. They have eight to ten tentacles that help them to swim and catch their prey. Squid, cuttlefish and octopus are cephalopods.