Echinoderms

Echinoderms are a diverse group of marine invertebrates that include brittlestars, starfish, sea lilies, feather stars, sea cucumbers, and sea urchins. There are about 6000 species of echinoderms. These creatures are mostly bottom dwellers, they live on the sea flore and employ a variety of feeding habits such as filter feeding, scavenging, and predation. Most living echinoderms are free-swimming, but they evolved from ancestors that were sessile (attached to the substrate).