Echinoderms are a group of marine invertebrates that includes sand dollars, sea stars, and sea cucumbers. Although many are not spiny like the sea urchin, the name echinoderms comes from the Greek for “spiny skin,” Sand Dollars, Sea Urchins, and Sea Stars share a five-part radial symmetry, like a pie cut into five pieces.
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- While alive, Sand Dollars are covered with fine brown velvety spines which are used to slowly move through the sand. The small central mouth can also be seen here.
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- It is illegal to keep live Sand Dollars found on our beaches. Loook, take pictures, but always release.
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- When Sand Dollars die, they quickly lose their spiny coating and the color will bleach out. If you sind a Sand Dollar like this, by all means, take it.
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- As they are not true fish, scientists prefer the name Sea Stars to Starfish. The underside is covered by tube feet and there is a central mouth.
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- A Lined Sea Star, the most commonly seen on the island. Sea Stars prey on bivalves, grasping the shell firmly to pry it apart. It only has to pry the shell open a fraction to insert its stomach through its mouth in order to digest the soft parts of the animal.
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- Sea Stars are sometimes carried long distances by ocean currents, but also move using their tube feet.
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- Common Sea Star, also fairly common on the island.
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- A mass beaching of Common Sea Stars.
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- Striped(Green) Sea Cucumber beached, has a tube-shaped body, tapered at each end. They often retain their boomerang shape in their burrows and when beached. Their tube feet are in relatively organized rows, giving them a lined appearance.
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- An itty, bitty Stripped Sea Cumber.
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- A Hairy (Brown) Sea Cumber is a soft gray-brown lump.
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- A Hairy Sea Cucumber may also have an almost spherical shape. They look hairy in life because of the tiny tube feet that cover their entire body.When beached, the “hair” is often worn off from the tumbling surf.
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- The sea cucumber will self-eviscerate, or expel its internal organs, as a defense mechanism if sufficiently stressed. The organs grow back over several days or weeks.
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- It is more commonly seen that they expel their sticky intestines, but they may also expel their digestive, respiratory, circulatory, and reproductive organs.
