Sea stars are related to brittle stars, sea urchins, feather stars and sea cucumbers and belong to the phylum echinoderm. This is an accurate description for these animals, as they have a spiny skin covering their skeleton. The skeleton of the sea stars is made up of many plates that move like flexible joints. Echinoderms are exclusively marine organisms, which are simple in external design, attractive in colour and, in some cases, have sharp spines. Holothuruid echinoderm, that is sea cucumbers, are bilaterally symmetrical like humans.
Sea stars are incredibly resilient.
When they lose an arm from their body it can regenerate into another one within a year. Provided that one fifth of the central disk and at least one arm remains, the original sea star can completely recover. Echinoderms possess tubed feet, this hydro-vascular system is used in collecting and transporting food and also in locomotion. Distribution and Habitat Sea stars can be found in most oceans around the world, on open coastal reefs, in sheltered waters and in open seas. The currents throughout the ocean disperse the larvae.