Black Corals

Very little information is available on Leiopathes corals. Their deep-water habitat suggests that, unlike many other corals, they do not possess the symbiotic algae, zooxanthellae, within their tissues. This means that they are not restricted to shallow, sunlit waters where the zooxanthellae can photosynthesise, and instead are able to inhabit deep and dark waters (6). It has recently been discovered that Leiopathes corals may be remarkably long-lived species. Research has revealed that Leiopathes glaberrima has a lifespan in excess of 4,000 years, making it the oldest known marine organism in existence (2).

Leiopathes corals are listed on Appendix II of the Convention on International Trade in Endangered Species (CITES), which means that any trade in this ancient coral that does take place should be carefully regulated, to ensure its future survival (1).

One of the oldest known organisms in the sea (2), Leiopathes corals have, like all other black corals (those belonging to the order Antipatharia), a dark skeleton, after which they are named. The black skeleton of Leiopathes corals forms irregularly branching, tree-like structures. It grows in a sympodial manner; rather than the first stem growing continuously upwards with branches arising from it, the first stem will stop growing after a certain time, and a new branch will grow out from the side. This too will eventually terminate growth, and a side branch will continue to grow, and so on (3). The skeleton is covered with polyps, the soft bodied, colourful part of the coral. Each polyp is attached to the skeleton at the base, while the other end bears a mouth surrounded by tentacles (4).

Leiopathes corals are deep water species, known to occur at depths of at least 450 metres (5).

The complete distribution of Leiopathes corals is not clear, but Leiopathes species have been recorded in the Atlantic and Pacific oceans (1).

Listed on Appendix II of CITES (1).

Many black corals are impacted by over-harvesting for the jewellery trade, where they are highly valued as their dark skeletons can be polished to a lustrous sheen (7). While Leiopathes glaberrima is currently not harvested, the discovery of its remarkably slow growth rates and old ages suggest that any exploitation of this species would not be sustainable (5), and therefore should be permanently banned (2). It is not clear whether other Leiopathes species are harvested, or whether they share the same incredible lifespan as L. glaberrima. Black corals around the world are also known to be impacted by habitat degradation, and recently, a small trade in live specimens for aquariums has been reported (7).