#echinodermata

• Asteroidea — A major taxonomic class of marine invertebrates in the phylum Echinodermata, grouping all true species of starfish; they are characterized by a flat central disc body from which multiple radiate arms (typically five) extend symmetrically, covered by a calcareous exoskeleton and equipped with tube feet for locomotion.
• Asterozoans — A major subphylum or taxonomic grouping (Asterozoa) within the phylum Echinodermata, bringing together all echinoderms with a star-shaped body and unchanging radial symmetry; it includes two major extant classes: Asteroidea (true starfish) and Ophiuroidea (brittle stars or ophiuroids).