ECHINODERMS

Echinoderms have a spiny body that usually divides into five equal parts. They walk on hundreds of tube feet that are full of water. If they lose part of their body, they can regrow it. They have a skeleton of calcium-carbonate plates.

LONG-LEGGED STARFISH

A starfish moves by pulling itself along on the sucker-like tube feet underneath its arms. These strong feet also enable the starfish to force open the shells of molluscs such as mussels or oysters. As the mollusc’s muscles weaken and the shell opens, the starfish pushes its stomach out through its mouth and into the shell to digest the mollusc.

SEA CUCUMBER

The sea cucumber’s tube feet are grouped around its mouth and filter food from the sand. If it is attacked, the cucumber pushes out its stomach and reproductive parts for the predator to take. The sea cucumber then grows replacement parts.

SPIKY URCHIN

Sharp spines cover the sea urchin’s hard skeleton and protect it from attack. Tube feet cover its body and spread between the spines. The sea urchin grazes on algae and small animals, with sharp jaws situated underneath its body.

PHYLUM: ECHINODERMATA

Most echinoderms are mobile, although sea lilies are stationary. They live on shores, reefs, and the seabed. There are about 6,000 species.

Class: Asteroidea

(starfish)

Features: central mouth on underside, surrounded by arms (usually five)

Class: Echinoidea

(sea urchins)

Features: spherical skeleton covered in spines

Class: Crinoidea

(feather stars, sea lilies)

Features: mouth faces upwards, feed on plankton

Class: Holothuroidea

(sea cucumbers)

Features: sausage-like body with tentacles around mouth

FIND OUT MORE

Communication
Defence

Copyright © 2007 Dorling Kindersley

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 Twitter icon Follow Us on Pinterest

editor’s picks

highlights

Join BIC on our mission to save handwriting and Fight For Your Write! Writing helps kids become better readers, boosts their confidence and sparks their creativity. Visit BICFightForYourWrite.com to sign our petition to save handwriting!

7 Fun Driveway and Sidewalk Games for Kids
Looking for classic outdoor games kids can play in the driveway or on the sidewalk, just like the good ol' days? From hopscotch to bubble-blowing contests, there's something for all ages!

Kindergarten Readiness App Wins Gold
Our Kindergarten Readiness app won the Gold Award of Excellence in the educational category at the 2014 Communicator Awards. This valuable checklist comes with games and activities to help your child practice the essential skills she needs for kindergarten. Download the Kindergarten Readiness app today!

Best Sun Safety Practices for Babies
Follow these sun safety practices for babies to ensure your little one stays safe on the beach and on sunny days all year long.