Long-spined Urchin

The main importance of the long-spined urchin to fisheries is through the reduction of algae. Long-spined urchins help control algae growth, which in turn promotes coral growth. Longspined urchins were one of the greatest consumers of algae on Caribbean coral reefs, but in 1984 a pathogen killed 95% – one of the most severe die-offs ever recorded in the Caribbean. Algae cover subsequently increased between 100% and 250%.
Long-spined urchins are herbivorous, feeding actively on algae and detritus (dead and decaying matter) during the night. They move slowly around the reef using a combination of their spines and podia, and scrape at the hard reef substrate with sharp angular teeth located around their mouth on the underside of the urchin. Long-spined urchins sometimes graze the sandy area immediately around the reef they hide on. This has the effect of leaving behind a ring of bare seabed, called an urchin halo, which is especially apparent around patch reefs. The decrease in abundance of long-spined urchins is partly to blame for the massive increase in algae on Caribbean coral reefs, as sea urchins are one the reef’s most important grazers.