Red coral

Corallium rubrum

Red coral (Corallium rubrum) is another soft octocoral and is endemic to the Mediterranean. The beautiful deep red colour is retained even after the animal is removed from the water and dried. It is much valued in the manufacture of jewellery, and the resulting unsustainable levels of harvesting have depleted this species in many areas. The powdered endoskeleton is also used by some practitioners of alternative medicine.

It tends to be found at depths in excess of 20m, to perhaps as deep as 300m and grows on hard substrates, with a preference for dark environments with minimal sedimentation. At shallower depths it is often found in caves, overhangs and crevices. In common with the indicator sea fans in section 3.3 above, it suffered a mass die-off in parts of the region, during 1999. Thought to be generally absent from the eastern Mediterranean, a number of colonies were discovered in some areas in the North Aegean Sea.

Red coral forms tree-style colonies with irregularly shaped branches. The calcium carbonate endoskeleton may reach a length of 60cm, but normally falls short of that. White polyps form the branches, each one with the characteristic 8 tiny tentacles or rays of the octocoral. The branches are covered with a bright red tissue, though occasionally these are white or even yellow. The inner limestone skeleton also contains carotene, resulting in the various shades of red that jewelers find so valuable.