• Sea Urchin

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  Sea Urchin facts and information:

  Common Name: Sea Urchin
  Scientific Name: Echinoidea
  Origin: Worldwide
  Size: 3-10cm (1.2-3.9in)
  Water Type: Salt
  Optimum pH Level: 6.0-9.0
  Life Span: 15-200 years

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  What is a sea urchin?

  Heart urchins and cake urchins are just some of the many species of sea urchins. These unusual animals provide an endless source of fascination. They are closely related to sea stars, sharing the same five-fold symmetry, and they too move about on hundreds of hydraulically operated tube feet. Sea stars and sea urchins are from a group known as echinoderms, a word meaning ‘spiny skins’. Sea urchin eggs have properties that make them important for medical research. Compounds extracted from marine organisms are initially tested to see whether they inhibit the production of rapidly dividing sea urchin eggs. If so, they may have potential to provide cures for AIDS, cancer and other diseases.

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  What does a sea urchin look like?

  There are nearly 200 different species of recognised sea urchin, that come in all shapes and sizes. Some sea urchins are covered in long thin spikes where others have a hard shell that is made up of chalky plates. The red sea urchin is the longest living creature on earth, with some living more than 200 years. Regular urchins are spherical animals with a case or shell of close-fitting limy plates. Sea urchins have spines that protect them from predators. However, it is mostly the hard outer shell, from which the spines have usually broken off, that is found washed up on beaches.
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  Where do sea urchins live?

  Sea urchins are found in all of Western Australia's marine parks. They are most common in intertidal habitats and on shallow reefs, but have been found as deep as 7000 metres. The sea urchin in found across the ocean floors worldwide, but rarely in the colder, polar regions.
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  What does a sea urchin eat?

  Sea urchins are omnivorous animals and therefore eat both plant and animal matter. The sea urchin mainly feeds on algae on the coral and rocks, along with decomposing matter such as dead fish, mussels, sponges ans barnacles. The mouth of the sea urchin is found in the middle on the underside of the sea urchin's body and has five tooth-like plates for feeding. As with other echinoderms, sea urchins do not have a brain and instead rely on their water-vascular system which is like a circulatory system and comprises of water-filled channels that run through the body of the sea urchin.

• What are the natural enemies of the sea urchins?

  Sea urchins are preyed about by many predators that inhabit their marine environment, but also those animals that don't. The main predators of the sea urchin are crabs, large fish, sea otters, eels, birds and humans. In some countries, certain species of the sea urchin are hunted and served as a delicacy.

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