The Echinoid Directory



Echinoida are exclusively epifaunal and the group today has members living in intertidal settings to depths of more than 2000 m. This group includes a number of important rock-borers such as Echinometra and Echinostrephus, and is well represented in shallow water rocky shore environments. All are either grazers, using their lantern to rasp at algal coatings in shallow water settings, or herbivores; the diet of deeper water taxa is almost certainly more mixed. Thier buttressed lantern structure and keeled teeth are evidence that they evolved primarily as raspers on hard substrates.

Geological history

The fossil record of Echinoida is particularly poor, partially because so many taxa preferentially live in habitats where fossilization potential is extremely low. Furthermore, correct assignment to this family depends upon having lantern structure preserved which is very rare. Based on external test morphology, however, some genera can be confidently assigned to this group, and show that it extends back to the early Eocene, and probably into the late Cretaceous.

The group has been diversifying towards the present, with Toxopneustids appearing by the mid Eocene, and Echinometrids by the late Eocene. This suggests that the principal clades were all established in the early part of the Tertiary.