Pelmatozoa
| Pelmatozoa | ||||||||||||
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Blastoidea from Haeckel's " Art Forms of Nature " |
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| Temporal occurrence | ||||||||||||
| Upper Cambrian to date | ||||||||||||
| 500 to 0 million years | ||||||||||||
| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Pelmatozoa | ||||||||||||
| Bather , 1900 |
The pelmatozoa (Pelmatozoa of Altgr. Πέλμα, sole 'and ζώα, animals') are a subtype of echinoderms . All pelmatozoa have a sessile way of life all the time or only in their youth and sit on the seabed with their side opposite the mouth, usually through a stalk that can be of different lengths. They are therefore also primarily called echinoderms with a stalk. There are about 620 recent species, all of which belong to the class of sea lilies and hair stars (Crinoidea). Over 3900 species have died out. They belong to the bud radiators (Blastoidea), the sac radiators (Cystoidea) and the Edrioasteroidea .
Pelmatozoa are likely the original form of all echinoderms. The body of the pelmatozoa is usually cup-shaped and surrounded on its upper side by numerous, mostly feathery arms. Their mouth and anus are on the same side of the body.
In the Paleozoic and early Mesozoic times the pelmatozoa were so numerous that entire limestone formations were formed in the mountains from their limestone plates and fossilized stalk limbs.
Classes
- † Bud radiators (blastoidea)
- † Bag emitter (cystoidea)
- † Edrioasteroidea
- Sea lilies and starfish (Crinoidea)
literature
- H. Füller, H.-E. Gruner, G. Hartwich, R. Kilias, M. Moritz: Urania Tierreich, Invertebrates 2 (Annelida to Chaetognatha) . Urania-Verlag, Leipzig 1994, ISBN 3-332-00502-2 .