Biology

Some Cirrhipathes corals have microscopic algae (zooxanthellae) living within their tissues (3). Through photosynthesis, these symbiotic algae produce energy-rich molecules that the coral polyps can use as nutrition. In return, the coral provides the zooxanthellae with protection and access to sunlight (4) (5). Those species without zooxanthellae must gain nutrition by another means, by capturing prey in their tentacles. Cirrhipathes species are known to capture any small organism floating in the ocean that measures up to two millimeters long, as well as large marine worms that may be over one centimetre in length (6). Cirrhipathes corals appear to provide a suitable environment for a number of species to inhabit, resulting in a number of fascinating relationships. The shrimps Pontonides unciger and Dasycaris zanzibarica are believed to only be able to survive living within a Cirrhipathes coral, while the male golden damselfish (Amblyglyphidodon aureus) bites off some of the living coral tissue to expose the bare skeleton beneath, where the female will lay her eggs. (6) The crab Xenocarcinus tuberculatus is also often found on Cirrhipathes corals, where it collects and covers itself with some of the coral polyps, in an ingenious attempt at camouflaging itself (6).