Starfish or sea stars are star-shaped echinoderms belonging to the class Asteroidea (/ ˌ æ s t ə ˈ r ɔɪ d i ə /). Common usage frequently finds these names being also applied to ophiuroids , which are correctly referred to as brittle stars or basket stars.

These small disc-shaped animals discovered in the abyssal seas off New Zealand and Bahamas in the late 1980s are considered an evolutionary forerunner to asteroids. Sea stars have an ancient linage that shows embryologically they are not too distantly related to the phylum Chordata (back-boned animals).

The Asteroidea is one of the largest and most familiar classes within the Phylum Echinodermata. These animals, commonly known as sea stars or starfishes, form a diverse and speciose group. There are approximately 1600 extant species (Hyman 1955; Clark 1977; Clark and Downey 1992) which are found throughout the world's oceans.

Apr 6, 2019 · While the classification name, "Asteroidea," may not be familiar, the organisms it contains probably are. Asteroidea includes the sea stars, commonly called starfish. With about 1,800 known species, sea stars are a variety of sizes, colors and are a …

5 days ago · The Asteroidea (also known as sea stars or starfish) are among the most diverse and familiar of the living Echinodermata, including over 1800 species from every ocean basin in the world, including the Atlantic, Indian, and Pacific as well as the Arctic and the Southern Ocean, inhabiting intertidal to 6000 m abyssal settings.

Mar 21, 2025 · sea star, any marine invertebrate of the class Asteroidea (phylum Echinodermata) having rays, or arms, surrounding an indistinct central disk. Despite their older common name, they are not fishes.

Apr 27, 2012 · The class Asteroidea (also known as starfish or sea stars) is one of the most diverse groups within the phylum Echinodermata, including nearly 1900 extant species grouped into 36 families, and approximately 370 extant genera.

May 26, 2020 · Class Asteroidea Snapshot. Examples: sea stars and starfish; Ecology: marine; Key features of group: Mobile epifaunal carnivore; Diversity: ~4,320 living sp., ~1,237 extinct sp. Fossil record: Ordovician to Recent

Aug 5, 2013 · Asteroids, popularly known as starfish or sea stars, are among the most readily recognized of marine animals. Asteroids are members of the Echinodermata, a major phylum of invertebrates that occurs exclusively in marine or near-marine settings and have a long and rich fossil history dating back to the early Paleozoic.

About 1,900 species of starfish live on the seabed in all the world's oceans, from warm, tropical zones to frigid, polar regions. They are found from the intertidal zone down to abyssal depths, at 6,000 m (20,000 ft) below the surface. Starfish are marine invertebrates.