Hedgehog Skins, the literal translation of Echinoderms, are the subject of the reef-stories here. The some 7000 species of Feather-Stars, Basket Stars, Starfish, Sea Urchins, Sand Dollars and Sea Cucumbers are found throughout the oceans. They are ecologically important in reefs, as predators, cleaners and as feathery hosts for entire communites of other animals as described in the feather-star party story
Note: this seach is a little slow the first time run, but then is fast. It is private and not tracked!
Starfish, Brittle Stars and Basket Stars all have a central disk with typically 5 arms, though some have many more. They are almost all generalist predators and a number of species are critical to the species diversity of the habitat they live in. This happens because they keep populations of quickly reproducing prey in check. Very sensitive to marine pollution, they are good bio-indicators. Pollution and over-exploitation consequently have impact on reef biodiversity.
The best known starfish on reefs is the Crown of Thorns (CoT). It is voracious feeder on corals, and when left unchecked, lays waste to large areas of reef. It has few natural predators. The Triton Trumpet Shell is the most effective predator, but its numbers have been decimated in many places by shell-collectors.