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

highlights

Special Books for the Kids You Love
Celebrate 20 years of sharing love to the moon and back with the anniversary edition of Guess How Much I Love You, one of the world’s best-loved picture books. Plus, search our Book Finder for more great book picks. Brought to you by Candlewick Press.

Vote Now for the Children's & Teen Choice Book Awards
Voting is open now through May 3 for the Children's and Teen Choice Book Awards — the only national book awards program where the winning author, illustrator, and books of the year are selected by young readers. Encourage your child to vote for his favorites today!

Top 10 Math & Science Apps for Your Whiz Kid
Looking for the best math and science apps for kids? Check out these cool apps for all ages, which will grow your child's love of the STEM subjects (science, technology, engineering, and math).

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