Edrioasteroidea

Cystaster stellatus from the Ordovician of northern Kentucky. Links below bryozoans.

• North America
• Europe

The Edrioasteroidea are an extinct class of echinoderms. They are among the oldest echinoderms, since the lower Cambrian in the fossil record to prove and died in Mittelperm from. Their diversity was low in the Ordovician appears with more than 20 genera of the peak of their diversity lie.

Features

The Edrioasteroidea were marine, sessile, but not sessile organisms that could probably suck with their underside, similar to sea anemones, to the substrate. Your capsule- like body ( theca ) was sliced ​​, sack - or tower- shaped or had the shape of a hemisphere. The diameter was usually between 15 and 30 mm, the minimum is 5 to 7 mm, the maximum of 90 mm. In the middle of the theca was covered by platelets mouth, ran out of the five Ambulacralfelder that ran mostly swung counterclockwise. The Ambulacralfelder are supported by a two-line - to floor panels. You are provided with pores, which can be closed secondarily. Sitting at the outer edges of Ambulacralfelder larger cover plates, to which, to the centerline of Ambulacralfelder, connect smaller cover plates. Through them the Ambulacralfüßchen were protected while the animal rested.

Way of life

The Edrioasteroidea lived in shallow water, ate probably as suspension feeders, filtered with their planktonic organisms Ambulacralfüßen from the passing water and led them through ciliated mucus webs to mouth.