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invertebrate

Sea Urchin

Frequently observed by snorkelers and divers, sea urchins are abundant in the Hawaiian Islands. Closely related to sea stars and sea cucumbers, these echinoderms are characterized by a globular or flattened skeleton called a test with hundreds of moveable spines, tube feet and tiny pincer-like organs called pedicellariae.

Spines on sea urchins vary upon species where some have sharp long spines and others have massive blunt spines. The spines serve as a mode of protection from various predators. Some species have venomous spines. The long-spined urchin or wana being one of the venomous species can inject a painful sting. Pain usually settles within a few hours but the spines will remain inside for extensive periods, eventually leading to your body absorbing them with no potential danger. Tube feet extend through the pores and are used to help cling and move along surfaces.

Reproduction happens through spawning where male and female urchins will simultaneously release eggs and sperm. Fertilize eggs then hatch into larvae that drift in the planktonic stage and later settle as bottom dwellers. Sea urchins generally graze on algae, with their mouth located on the underside.

In old Hawaii the spines were used for carving, as well as a food source as the gonads were considered a delicacy for many. For others that had an urchin appear in a dream or vision held these animals as having a special meaning. Roughly 75 known species inhabit the Hawaiian waters, 22 more commonly inhabiting shallow waters.

*Due to the constant rotation of animals back to the ocean, the presence of any specific animal cannot be guaranteed.

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