Gorgonian (order Alcyonacea)

Any group of animals known as ‘Gorgonians’ is bound to be amazing, right? Well, maybe. You may be picturing some monster with snakes for hair, but unfortunately gorgonians are much more tame than actual gorgons. They’re still pretty cool, though!

Gorgonians are part of the order Alcyonacea (formerly Gorgonacea), and are also known as sea whips or sea fans. I’m not going to go into individual species of gorgonians, because there are around 500 of them, and that would take quite a while. Gorgonians are found in large numbers in the western Atlantic, especially in Florida, Bermuda and the West Indies. Most species prefer shallow waters, though some do inhabit deeper waters.

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You can’t deny gorgonians are pretty. Image credit: Jaro Nemčok via Wikipedia

Gorgonians are a type of soft coral, and are made up of very small individual polyps. So a single sea fan is actually a colony of thousands of tiny little animals, joined together into a big pretty structure. How cool is that? Common shapes of gorgonians are fan- and whip-like structures, though some are bushy. Colonies can get pretty large, reaching over a meter in length and height, but are usually quite thin. Different species are different colours, with common ones being red, yellow or purple.

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A close up of a gorgonian, showing the tentacles of the polyps that make up these fascinating creatures. Image source: Wikipedia

The hardened skeletons of gorgonians are composed of different minerals, depending on the species. One such substance is known as gorgonin, which is a protein high in bromine, iodine, and tyrosine. The cool part about gorgonin is that the amount and composition of the protein varies with changes in season and climate. So for gorgonian species that are very long lived, their skeletons are useful for the study of paleoclimatology and paleoceanography.

The polyps that make up gorgonians have eight tentacles, which are used for filter feeding. To maximize the amount of food that reaches these polyps, fan-like gorgonians orient themselves across the prevailing currents. Some gorgonians don’t rely solely on filter feeding — they have symbiotic relationships with algae and zooxanthellae. These organisms are able to photosynthesize, which gives the gorgonians another source of food.

There are other creatures that make gorgonians their homes, such as hydrozoa, byrozoa and brittle stars. Pygmy seahorses are particularly fond of gorgonians, and have evolved to look like their hosts. Some species of seahorse are so dependent on this camouflage that they can’t live anywhere but on a gorgonian.

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A pigmy seahorse on its gorgonian home. Image credit: Jens Petersen via Wikipedia

Corals and gorgonians might not look like the most exciting animals around, but there’s a lot more going on with these guys than you think. The colonies do look quite pretty, but they also provide homes for a number of creatures, especially cute ones like pygmy seahorses. So don’t under appreciate gorgonians!

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