Echinozoa is a subphylum of free-living echinoderms in which the body is essentially globoid with meridional symmetry. Echinozoans lack arms, brachioles, or other appendages, and do not at any time exhibit pinnate structure. Their two extant classes are the sea urchins and the sea cucumbers.
|The melon sea urchin (Echinus melo) in northwest Sardinia|
† = Extinct