This unusual coral is a Ctenactis Echinata, a species of mushroom coral, so named due to their similarity to the cap of a mushroom and I saw it at the Secret Cities of the Sea exhibition. Most mushroom corals are free-living rather than colonial and sit by themselves in crevasses and on the edge of kelp forests. Many mushroom corals also looked bleached due to a lack of zooxanthelles, symbiotic algae, in their bodies which is unusual for a coral and as such many people mistake them for dead. Luckily, unlike the coral reefs we are used too, bleaching in many species of mushroom coral is perfectly healthy.
The specimen above is particularly round in shape, ctenactis echinata normally being more of an oval pattern around 20-30cm long and roughly half that in width. Like most mushroom coral, this coral has a single mouth opening on the top of its body, through which polyps will emerge at night in order to feed. The edged plates that make up the radius of the coral are sharply edged with tiny teeth, that can badly cut attackers although, other than specialised coral eaters, this species doesn’t have much to fear except from attacks by other coral. This species does not appear bleached, instead having a dark brown colour while alive, that makes it look similar to the rocks it nestles amongst.
The Ctenactis Echinata can both reproduce with the use of spawning, in which all corals simultaneously release eggs and sperm into water, or by sprouting off smaller versions of itself to create genetically identical clone corals. Asexual reproduction like this is often done when the current coral is to badly injured to continue living for long, and such a measure is required to ensure the corals genes continue to exist. Fortunately for the coral, its genetics do not seem under threat, being rated as one of the least concerning species in terms of its rarity. This is perhaps due both to its enormous distribution, across most of the Pacific from China to the Red Sea to Australia, and the lengths to which it will go in order to survive.
It is almost impossible to go diving in the Pacific ocean without coming across on of these corals or one of its mushroom coral cousins. If I am able to pursue diving in those areas I’m sure I will see it.