English: Sea urchins.
Clades:
Echinodermata;
Deuterostomia;
Animals.
Genera: 950 species.
Region: all oceans.
Habitat: seabed; all depth zones from the intertidal to 5,000 metres.
ZoologyEchinoidea are globular animals. They have tests, hard shells that are round and spiny, usually from 3 to 10 cm across.
They move slowly, crawling with their tube feet, and sometimes pushing themselves with their spines.
They feed primarily on algae but also eat slow-moving or sessile animals.
Their predators include sea otters, starfish, wolf eels, triggerfish, and humans.