Members of this family have anywere from 5 to 15 arms. Several species in this taxa are of considerable size. One species Luidia superba from the Galapagos is one of the largest asteroids in the world. This is an entirely deep-sea group inhabiting infaunal habitats. Representatives of this group are found in the deepest of the world's oceans.
Many taxa have cosmopolitan distributions.
This is a monotypic group including only the genus Radiaster with four species. All are found in relatively deep-water. Notomyotida Benthopectinidae 12 valid genera. Benthopectinids are an exclusively deep-sea taxon of asteroids found in the Atlantic and Pacific Oceans. This monotypic multi-armed family represents the genus Acanthaster with two species planci and brevispinis.