CRUSTACEANS

Crustaceans have a hard, jointed external skeleton, called an exoskeleton, that protects them like armour. They have five pairs of jointed legs, and in some species, the front pair of legs are modified to form strong pincers. Crustaceans have compound eyes (made up of lots of lenses) on stalks and two pairs of antennae, which help them to sense predators. Most crustaceans live in water, but some, such as woodlice, live in damp places on land.

JOINTED BLUE L0BSTER

The common lobster is blue, and can be as much as 1 m (3 1/4 ft) long. Lobsters have a jointed body, a long abdomen, and a wide tail fan. As the lobster grows, it gets too big for its hard shell, or carapace. The shell splits, the lobster crawls out, and a new shell hardens. Lobsters feed at night, cracking open molluscs with their huge claws.

BARNACLE BABY

Some crustaceans, such as barnacles, can only move about as larvae. Barnacles lay eggs that hatch into larvae and move away. These drift freely as they grow, before attaching themselves to a rock, the bottom of a ship, or a whale, and changing into the adult form. The adult barnacle cannot move around.

KRILL

Krill use long hairs on their front legs to filter food particles from the seawater. They have a soft body and large eyes. They are sociable, often living in huge swarms, and are important in the marine food chain. Baleen whales feed on nothing but krill.

LOPSIDED CRAB

Most crustaceans have two claws that are the same size, but the male fiddler crab has one enormous claw and one tiny one. It waves the giant claw about in order to attract a mate and also to frighten away competing males. The huge claw can make up half of the crab’s total weight. Fiddler crabs live in mangrove swamps, where they make burrows in the mud.

PHYLUM: CRUSTACEA

Most crustaceans live in water. There are more than 45,000 species in seven classes, including:

Class: Branchiopoda

(fairy shrimps, water fleas)

Features: small, free-living, filter feeders with bristled mouthparts

Class: Cirripedia

(barnacles)

Features: box-like bodies, sessile (anchored to one spot) as adults

Class: Malacostraca

(crabs, lobsters, prawns, woodlice)

Features: jointed legs, often pincers, eyes on stalks

FIND OUT MORE

Animal Anatomy
Senses

Copyright © 2007 Dorling Kindersley

highlights

Teens and E-Cigarettes: 6 Things You Must Know
For the first time in a generation, tobacco use has risen among the nation's youth, due to the rising use of e-cigarettes. Learn more about the dangerous and addictive e-cigarette trend, and get tips to talk to your teen.

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.

Printable Lists of the Top 100 Baby Names
Need help with baby name ideas? Use our printable list of the top 100 girl names and top 100 boy names of 2015 to help you brainstorm and narrow down your favorites.

Registered for Kindergarten — Now What?
Wondering what to do now that you've signed your child up for kindergarten? 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