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Strongylocentrotus purpuratus |
THE RACE ROCKS TAXONOMY | |
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| Purple Urchins and Californianus mussels at a "zero" level tide on the west side of Great Race Rocks. July 2000 |
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| In this video, a Pearson College student provides an introduction in Portuguese | ||||||||||||||||||||||||||||||||||
| This video compares the purple,green and red sea urchins. | ||||||||||||||||||||||||||||||||||
| Sea Urchin Embryology Lab | ||||||||||||||||||||||||||||||||||
| The purple sea urchin is about 10 cm. across, spines up to 2cm. and is bright purple. Its body "skeleton", called the test, is shell like with bumps and holes from which the moveable spines and tube feet extend .The spines are used for protection, movement and for trapping drifting algae. It has a claw like mouth with 5 teeth-like plates. It is composed of over 60 shells and is called Aristotle's lantern and is located on the underside or oral side of its body. The anus and the genital pores are on the aboral side of the sea Urchin.
Diet: The Sea Urchin feeds on algae, plankton, kelp, periwinkles, and occasional tiny barnacles or mussels. They are eaten by crabs, sunflower stars, snails, sea otters, some birds, fish, and people. Reproduction: Fertilization in Sea Urchin is external, the female release several million tiny, yellow jelly-coated eggs at a time. The gametes join the water column as planktonic forms . Behaviour: Although they often live in sheltering holes that they have worn in the rocks and they have also been observed to makes holes in solid steel, this behaviour is not evident at Race Rocks. Most of them live in shallow water here, They move surprisingly fast on their tube feet and spines. Moving their feet by a hydraulic water vascular system which creates suction in the end of the foot by pulling water out of the madreporite. They can also regrow broken spines. The following images show the structural features on the test of a dead purple sea urchin. The image was produced by scanning.
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| The image above shows the oral view of a purple sea urchin. The hole in the middle is its mouth with the sharp edges its 5 teeth. Note the pentaradial symmetry. | ||||||||||||||||||||||||||||||||||
| The above image shows the aboral view of a purple sea urchin.The dark patch in the middle is the anus. These were dead specimens.Thus the spines are missing. | ||||||||||||||||||||||||||||||||||
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