| Later eocrinoids evolved a long stalk with columnals, like crinoids and blastoids. |
| Equally well represented in these waters are invertebrates such as crinoids, nudibranchs and featherduster worms. |
| Some sea cucumbers are able to float or swim, and a few stalkless crinoids are also capable of swimming for short periods. |
| The arms of ophiuroids and crinoids are supported by calcitic ossicles reminiscent of vertebral centra. |
| In most extant crinoids, primarily the shallow-water ones, there are two body regions, the calyx and the rays. |
| In unstalked crinoids, the cirri are located on the end of the calyx opposite the mouth, and are used by the animal to grasp the substratum. |
