Monotypic echinoderm genera

thumb|Detail view Choriaster is a monotypic genus in the family Oreasteridae, containing the single species Choriaster granulatus, commonly known as the granulated sea star. Other common names include big-plated sea star, hunter-five sea star and doughboy starfish.

Loxechinus albus is an echinoderm of the family Parechinidae, native to coastal southern South America, ranging from Ecuador, along the entire coasts of Peru and Chile, to Argentina, as well as the Falkland Islands. It is the only species in the genus Loxechinus. It is known as the Chilean sea urchin or red sea urchin, but the latter name is typically used for the North Pacific Mesocentrotus franciscanus and it is not the only species of sea urchin in Chile (although it is the most common and widespread large sea urchins in that country). L. albus is found on rocky reefs and shores in the inte

Astrophyton muricatum, the giant basket star, is an echinoderm found in shallow parts of the tropical western Atlantic and throughout the Caribbean Sea and the Gulf of Mexico. It is the only species in the genus Astrophyton. During the day, it curls up into a tight ball shape to protect itself from predators. At night, it climbs to an elevated point to feed by extending its intricately branched feeding arms in a bowl-like shape in order to snare passing plankton and other organisms from the current.

Hemicentrotus pulcherrimus is a species of sea urchin, the only one in the monotypic genus Hemicentrotus. It was first described by the American engineer and marine zoologist Alexander Agassiz in 1864 as Psammechinus pulcherrimus. Its range extends along the coasts of Korea, Taiwan and China, and in Japan from Kyūshū to Ishikari Bay. An edible species, it is harvested from Kyūshū to Fukui, in the Sea of Japan.

Bathyporania ascendens is a species of starfish in the family Poraniidae, and the only species of the genus Bathyporania. It is native to the Pacific Ocean and is found in deep water off the coast of North America (it was discovered at Davidson Seamount).

Clavaporania fitchorum is a species of starfish in the family Poraniidae. It is the only known species of the genus Clavaporania. It is native to the South Pacific Ocean and is found in deep water off the coast of Australia (it was discovered at Hjort Seamount, south of Macquarie Island).

Meyenaster is a genus of starfish in the family Asteriidae. It is a monotypic genus and the only species is Meyenaster gelatinosus which was first described by the Prussian botanist and zoologist Franz Julius Ferdinand Meyen in 1834. It is found in the southeastern Pacific Ocean on the coasts of South America.

thumb|Australostichopus mollis at Bicheno, Tasmania

Parechinus angulosus, the Cape urchin, is a sea urchin in the family Parechinidae endemic to southern Africa. It is the only species in the genus Parechinus.

Stylasterias is a genus of starfish in the family Asteriidae. Stylasterias forreri, the velcro star, is the only species in the genus. It is found on the Pacific coast of Canada and the United States.

Asterechinus elegans is a species of sea urchin of the family Trigonocidaridae. Their armour is covered with spines. It is the only species in the genus Asterechinus and lives in the sea. Asterechinus elegans was first scientifically described in 1942 by Ole Theodor Jensen Mortensen.

Glabraster is a genus of starfish in the family Poraniidae. It is monotypic, the sole species being Glabraster antarctica. It is also known as the red spiny cushion star.

Pearsonothuria is a genus of sea cucumbers in the family Holothuriidae. Pearsonothuria graeffei is the only species in the genus. '''Graeffe's sea cucumber''' is found in the tropical Indo-Pacific Ocean and the type locality is Viti Island, Fiji. It is named after Eduard Heinrich Graeffe, Semper's coworker at the Museum Godeffroy.

Orthasterias is a genus of sea stars in the family Asteriidae. Orthasterias koehleri, the rainbow star or red-banded sea star, is the only species in the genus. It is found in the North Pacific Ocean.