Sea urchins are spiny, globular echinoderms in the class Echinoidea. About 950 species of sea urchin are distributed on the seabeds of every ocean and inhabit every depth zone from the intertidal seashore down to 5,000 meters. The spherical, hard shells (tests) of sea urchins are round and covered in spines. Most urchin spines range in length from 3 to 10 cm, with outliers such as the black sea urchin possessing spines as long as 30 cm (12 in). Sea urchins move slowly, crawling with tube feet, and also propel themselves with their spines. Although algae are the primary diet, sea urchins also eat slow-moving (sessile) animals. Predators that eat sea urchins include a wide variety of fish, starfish, crabs, marine mammals, and humans.
Littorina is a genus of small sea snails, marine gastropod molluscs in the family Littorinidae, the winkles or periwinkles.
The Diadematidae are a family of sea urchins. Their tests are either rigid or flexible and their spines are long and hollow.
Diadema antillarum, also known as the lime urchin, black sea urchin, or the long-spined sea urchin, is a species of sea urchin in the family Diadematidae.
Cidaris is a genus of pencil sea urchins.
Bald sea urchin disease is a bacterial disease known to affect several species of sea urchins in the Mediterranean Sea, North Atlantic and along the California coastline. Research suggests two pathogens are responsible for the disease, Listonella anguillarum and Aeromonas salmonicida.
Eucidaris tribuloides, the slate pencil urchin, is a species of cidaroid sea urchins that inhabits littoral regions of the Atlantic Ocean. As a member of the basal echinoid order Cidaroida, its morphological, developmental and molecular genetic characteristics make it a phylogenetically interesting species.
Cidaroida is an order of primitive sea urchins, the only living order of the subclass Perischoechinoidea. All other orders of this subclass, which were even more primitive than the living forms, became extinct during the Mesozoic.
Lischkeia is a genus of sea snails, marine gastropod molluscs in the family Eucyclidae.
Cidaridae is a family of sea urchins in the order Cidaroida.
Abatus cavernosus is a species of sea urchin of the family Schizasteridae. Their armour is covered with spines. It is in the genus Abatus and lives in the sea. Abatus cavernosus was first scientifically described in 1845 by Rodolfo Philippi. Females brood their young in a brood pouch through the gastrula stage until they are juveniles.
Cidaris cidaris is a species of sea urchin commonly known as the long-spine slate pen sea urchin. It is found in deep water in the eastern Atlantic Ocean and the Mediterranean Sea.
Cidaris abyssicola is a species of sea urchin in the Family Cidaridae. Cidaris abyssicola was first scientifically described in 1869 by Alexander Emanuel Agassiz.
Cidaris blakei is a species of sea urchins of the family Cidaridae. Its armour is covered with spines of three types, one unique type being extended and fan-like, making it easily recognized. Alexander Agassiz first described it scientifically in 1878. It is present on the seabed in deep waters in the Gulf of Mexico and the Bahamas.
Cidaris mabahissae is a species of sea urchins of the Family Cidaridae. Their armour is covered with spines. Cidaris mabahissae was first scientifically described in 1939 by Ole Mortensen.
Cidaris nuda is a species of sea urchins of the Family Cidaridae. Their armour is covered with spines. Cidaris nuda was first scientifically described in 1903 by Ole Mortensen.
Cidaris rugosa is a species of sea urchins of the Family Cidaridae. Their armour is covered with spines. Cidaris rugosa was first described in 1907 by Hubert Lyman Clark as Dorocidaris rugosa.
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.
Abatus is a genus of sea urchins belonging to the family Schizasteridae.
Stylocidaris is a genus of echinoderms belonging to the family Cidaridae.
