1.Sea Stars Are Echinoderms, Not Fish
Despite commonly being called starfish, sea stars are not a fish species. They do not have gills, scales, or tails like fish. They also do not have a backbone, so they are considered an invertebrate species. More specifically, they belong to a family called Echinoderms. Being an Echinoderm means that members of these species have five-point radial symmetry (even though some sea stars have different numbers of arms! (See fact number 2) Some other species in the Echinoderm family include, sand dollars, sea urchins, and sea cucumbers. Another interesting characteristic that makes sea stars unique is how they move through the water. They have small tube feet under their body that helps to propel them through the water. These feet also have suction cups which allows the sea star to attach to rocks and prey. There are approximately 2,000 sea star species, all of which exist in ocean habitats.