The subclass Euechinoidea includes almost all living species of sea urchin, and fossil forms going back as far as the Triassic.
The Aspidodiadematidae are a family of sea urchins.
Diadema is a genus of sea urchins of the family Diadematidae.
The heart urchins or Spatangoida are an order of sea urchins.
Temnopleuridea is an infraorder of sea urchins in the order Camarodonta. They are distinguished from other sea urchins by the presence of large fused plates on top of the feeding lantern. The test is usually sculpted to some degree, and has perforated tubercles.
The Echinothurioida are an order of sea urchins in the class Echinoidea. Echinothurioids are distinguished from other sea urchins by the combination of a flexible test and hollow spines. The membrane around the mouth contains only simple plates, in contrast to the more complex mouth parts of their close relatives, the Diadematoida. They are nearly all deepsea dwellers.
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.
The Camarodonta are an order of globular sea urchins in the class Echinoidea. The fossil record shows that camarodonts have been in existence since the Lower Cretaceous.
Sterechinus is a genus of sea urchins in the family Echinidae. All living members of the genus are found in the waters around Antarctica but the first species described in the genus was a fossil and was found in Europe.
Sterechinus neumayeri, the Antarctic sea urchin, is a species of sea urchin in the family Echinidae. It is found living on the seabed in the waters around Antarctica. It has been used as a model organism in the fields of reproductive biology, embryology, ecology, physiology and toxicology.
Holasteroida is an order of irregular sea urchins.
Lytechinus williamsi, the jewel urchin, is a sea urchin in the family Toxopneustidae. It occurs on shallow reefs off the coasts of Panama, Belize, the Florida Keys and Jamaica.
Aspidodiadema arcitum is a species of sea urchin of the family Aspidodiadematidae. Their armour is covered with spines. It is placed in the genus Aspidodiadema and lives in the sea. Aspidodiadema arcitum was first scientifically described in 1939 by Ole Theodor Jensen Mortensen, a Danish scientist.
Calveriosoma gracile is a species of sea urchin in the order Echinothurioida. It is a deep water species and is found on the seabed in western parts of the Pacific Ocean at depths of 200 to 800 metres.
Irregularia is an extant infraclass of sea urchins that first appeared in the Lower Jurassic.
The infraclassis Carinacea includes most living species of regular sea urchin, and fossil forms going back as far as the Triassic.
The Echinothuriidae are a family of sea urchins in the order Echinothurioida. Due to their soft skeletons, most are called "leather urchins", but species in the genus Asthenosoma are also known as "fire urchins" due to their bright colors and painful, venomous sting.
Strongylocentrotus fragilis is a species of sea urchin of the family Strongylocentrotidae.
Asterocidaris is a genus of fossils sea urchins in the family Hemicidaridae. These epifaunal grazer-deposit feeders lived in the Middle and Upper Jurassic age.
