MOLLUSCS

Slugs, snails, oysters, clams, squid, octopuses, and cuttlefish are very different to look at, but they are all molluscs. They have a ribbon-like tongue, called the radula, covered in thousands of denticles (tiny teeth). Many have a calcium-carbonate shell. Most molluscs live in water, but slugs and snails live on land.

GIANT SNAIL

The African land snail can be 30 cm (12 in) long. Like all snails, it carries a coiled shell on its back and withdraws into the shell when threatened. It moves slowly on a large, muscular foot, using slime to ease the way. Its mouth, underneath its head, contains the denticle-covered radula.

INTELLIGENT OCTOPUS

The blue-ringed octopus is a mollusc that does not have a shell. It has a large brain and big eyes. It uses its eight arms to crawl, but also squirts water from inside its body to move more quickly.

PHYLUM: MOLLUSCA

Molluscs have unsegmented bodies generally protected by a shell. There are more than 50,000 species in seven classes, including the following five common ones.

Class: Bivalvia

(clams, mussels, oysters, scallops)

Features: shell in two symmetrical halves with hinge

Class: Polyplacophora

(chitons)

Features: shell made up of several overlapping plates

Class: Gastropoda

(snails, slugs)

Features: suction foot, many have spiral shell

Class: Scaphopoda

(tusk shells, razor shells)

Features: long, tubular shells, burrow into sediment

Class: Cephalopoda

(nautiloids, squid, octopus)

Features: tentacles, suckers

Copyright © 2007 Dorling Kindersley

highlights

11 Awesome STEM Toys to Get Kids into Science & Math
Get your child excited about the STEM subjects (science, technology, engineering, and math) and summer learning! See our picks for science kits, math games, and other STEM toys for kids of all ages.

Find Today's Newest & Best Children's Books!
Looking for newly released books for your child? Try our new Book Finder tool to search for new books by age, type, and theme, brought to you by Galactic Hot Dogs.

Preventing Hot Car Deaths: 6 Facts & Tips for Parents
Every year, between 30 and 50 children in the U.S. die from overheating in a vehicle. Learn facts and prevention tips to safeguard your child from "hot car death."

Registered for Kindergarten — Now What?
Try our award-winning Kindergarten Readiness app! This easy-to-use checklist comes with games and activities to help your child build essential skills for kindergarten. Download the Kindergarten Readiness app today!

stay connected

Sign up for our free email newsletters and receive the latest advice and information on all things parenting.

Enter your email address to sign up or manage your account.

Facebook icon Facebook icon Follow Us on Pinterest

editor’s picks