Echinodermata
English: Echinoderms.
Name: Echinodermata means spiny skin; from echinos meaning sea-urchin, and derma meaning skin.
Habitat: marine aquatics; at every ocean depth, from the intertidal zone to the abyssal zone; no freshwater or terrestrial representatives.
Genera: 7500 species.
Zoology
They are starfish, sea urchins, sand dollars, sea cucumbers.
They usually have a five-point, radial symmetry.
They have remarkable regeneration of tissues, organs, limbs, complete regeneration from a single limb.
Reproduction: asexual.
Body: ossified skeletons, contributors to many limestone formations; maybe the radiation of echinoderms was responsible for the Mesozoic revolution of marine life.
Clades
1 Crinoidea (feather stars), sessile
1.1 Pelmatazoa: crinoids, sessile; feather stars, have secondarily re-evolved a free-living lifestyle.
Families: Comatulida, Cyrtocrinida, Hyocrinida, Isocrinida
2.1 Echinoidea: sea urchins and sand dollars.
2.1 Holothuroidea: sea cucumbers
3 Asterozoa, motile
3.1 Ophiuroidea: brittle stars + basket stars.
3.2 Asteroidea: starfish
3.2.1 Concentricycloidea: sea daisies