Starfish Starfish Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea. Common usage frequently finds these names being also applied to ophiuroids, which are correctly referred to as brittle stars or "basket stars". About 1,500 species of starfish occur on the seabed in all the world's oceans, from the tropics to frigid polar waters. They are found from the intertidal zone down to abyssal depths, below the surface. Starfish are marine invertebrates. They typically have a central disc and five arms, though some species have a larger number of arms. The aboral or upper surface may be smooth,
Phylum for Chromista and Protozoa by the Catalogue of Life, adapted from the system used by the International Society of Protistologists. The Catalogue of Life includes Rhodophyta and Glaucophyta in kingdom Plantae, but other systems consider these phyla part of Protista. Currently there are 29 phyla accepted by List of Prokaryotic names with Standing in Nomenclature (LPSN) Currently there are 5 phyla accepted by List of Prokaryotic names with Standing in Nomenclature (LPSN). Phylum In biology, a phylum (; plural: phyla) is a level of classification or taxonomic rank below Kingdom and above Class. Traditionally, in botany the term division has