It s a catalyst to spur interest and curiosity in deep sea fauna. More than 150 species of black coral are described. Shapes vary from a single, whip-like axis to an elaborate tangle of branches. They occur in all oceans, but are most common in deep water habitats of tropical seas. At least 14 are currently known from Hawai'i.
Black corals are colonial animals related to sea anemones and stony corals.
This means they are not limited to sunlit reaches of the reef and can occur in caves and under ledges, as well as at great depth. They are also made of different stuff than the corals we usually see in shallow water reefs. They have a protein and chitin skeleton, like an insect exoskeleton, which gives them that black appearance. Depending on the species, the living tissue may be black, orange, brown, yellow or white. To feed, black coral polyps must capture food particles with their tentacles, some of which are armed with nematocysts.