Coral Reef

Coral reefs, and their associated systems of mangroves and seagrasses, are the world's most biologically diverse marine ecosystems. Reef building corals contain tiny cells of symbiotic algae that convert sunlight and nutrients into fuel for coral growth and production. Other types of corals that do not require warm water or sunlight are found in deep water, providing important habitats for commercial, recreational and other species.

Boulder and massive corals, like this boulder star coral, are the "builders" of the reef. A coral head is a colony of small animals called polyps. These corals provide the reef foundations that is home to millions of reef species. Over 4,000 species of reef fish have been described so far.

Elkhorn coral is a branching coral. Branching corals grow in the shallow areas of the reef crest and serve to break up the wave action as it comes onto the reef. The branches of elkhorn coral resemble an elk's rack of antlers, thus its name.

Pillar coral forms numerous heavy cylindrical spires that grow upward from an encrusting base. Unlike other hard corals, which feed at night, pillar coral extends its polyps to feed during the day. Fallen pillers may give rise to new upward growing