Echinodermata
Echinodermata (e*kī`no*dẽr"mȧ*tȧ) , noun, plural
[New Latin, from Greek 'echi^nos hedgehog, sea urchin + de`rma, -atos, skin.]
(Zoology) One of the grand divisions of the animal kingdom. By many writers it was formerly included in the Radiata.
The species usually have an exterior calcareous skeleton, or shell, made of many pieces, and often covered with spines, to which the name. They may be star-shaped, cylindrical, disk-shaped, or more or less spherical. The body consists of several similar parts (spheromeres) repeated symmetrically around a central axis, at one end of which the mouth is situated. They generally have suckers for locomotion. The group includes the following classes: Crinoidea, Asterioidea, Ophiuroidea, Echinoidea, and Holothurioidea. See these words in the Vocabulary, and also Ambulacrum.