Classification
There are five main classes of Echinoderms:
- Sea Stars or starfish (Asteroidea)
- Brittle stars, basket stars, serpent stars (Ophiurodea)
- Sea urchins, heart urchins and sand dollars (Echinoidea)
- Holothurians or sea cucumbers (Holothuroidea)
- Feather stars and sea lilies (Crinoidea)
Sea stars or starfish are classified as follows:
- Kingdom : Animalia
- Phylum : Echindermata
- Class: Asteroidea
Echinodermata means 'spiky skin' and Asteroidea means 'star-like'. There are seven orders of starfish and about 1500 living spacies. All are marine.
Characteristics
Charateristics of Echinoderms include:
- radial symmetry
- several arms radiating from a central body (5 or more, mostly grouped 2 left, 1 middle and 2 right)
- body consists of 5 equal segments each of which contain a duplicate set of internal organs
- have no heart, brain or eyes (starfish have eyespots)
- have small structures called tube feet with suction cups on the ends that are hydraulically controlled
Website created by Jenny Stevenson - June 2006.
