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Two species of sea urchin

Sea urchins are a group of spiny globular echinoderms which form the class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to 5,000 metres (16,000 feet; 2,700 fathoms). Their tests (hard shells) are round and spiny, typically from 3 to 10 centimetres (1 to 4 inches) across. Sea urchins 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, and triggerfish. This photograph, taken off the northern coast of Haiti near Cap-Haïtien, shows two species of sea urchin: a West Indian sea egg (top) and a reef urchin (bottom).

Photograph credit: Nick Hobgood, edited by Lycaon

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From Wikipedia, the free encyclopedia

Today's featured picture

Two species of sea urchin

Sea urchins are a group of spiny globular echinoderms which form the class Echinoidea. About 950 species live on the seabed, inhabiting all oceans and depth zones from the intertidal to 5,000 metres (16,000 feet; 2,700 fathoms). Their tests (hard shells) are round and spiny, typically from 3 to 10 centimetres (1 to 4 inches) across. Sea urchins 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, and triggerfish. This photograph, taken off the northern coast of Haiti near Cap-Haïtien, shows two species of sea urchin: a West Indian sea egg (top) and a reef urchin (bottom).

Photograph credit: Nick Hobgood, edited by Lycaon

Other areas of Wikipedia

  • Community portal – The central hub for editors, with resources, links, tasks, and announcements.
  • Village pump – Forum for discussions about Wikipedia itself, including policies and technical issues.
  • Site news – Sources of news about Wikipedia and the broader Wikimedia movement.
  • Teahouse – Ask basic questions about using or editing Wikipedia.
  • Help desk – Ask questions about using or editing Wikipedia.
  • Reference desk – Ask research questions about encyclopedic topics.
  • Content portals – A unique way to navigate the encyclopedia.

Wikipedia's sister projects

Wikipedia is written by volunteer editors and hosted by the Wikimedia Foundation, a non-profit organization that also hosts a range of other volunteer projects:

Wikipedia languages


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