Page 63 - Caribbean Reef Life Demo

Sea urchins are protected by long mobile spines that are also used for moving about the reef. They rarely venture out in the day, hiding in crevices until nightfall when they come out and clean the reef of algae and decaying plant and animal matter. As reef cleaners, sea urchins are essential to the entire reef ecosystem. In 1983 a mysterious disease killed off 97 of the Long-Spined rchins and most Caribbean reefs uickly suffered: the algal bloom that followed caused the amount of algae-covered corals to increase by as much as 250 . Many reefs have still not fully recovered to this day.
Sea urchins reproduce in summer by releasing millions of jelly-covered eggs and clouds of sperm into the water. The larvae can drift for up to six weeks until they develop enough to settle onto a new reef and begin foraging.
Between the spines of some sea urchins there are tiny tentacles called podia, with miniature suction cups on the ends. They use these to cling onto reef walls and to move about, climbing over obstacles. Some sea urchins use these podia to grab onto loose bits of dead algae or empty shells. This covering gives them extra protection and camou age on the reef.
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