Gorgonians are sessile colonial animals in the class Anthozoa, which includes other invertebrates like corals and sea anemones. They are also known as sea fans and sea whips.
There are around 500 known gorgonian species found mostly in shallow waters, attached to a hard substrate. They have an internal skeleton with forms ranging from flat and branching to encrusting and whip-shaped.
Usually fan-shaped gorgonians are more flexible and live in shallow areas where currents are stronger, while gorgonians in deeper, more still waters are usually stiffer, taller, and thinner, with some species even able to live down to around 300 meters (1,000 feet) below the sea surface.
Gorgonians are filter feeders, with each polyp in a colony using its eight tentacles to capture planktons and other particles in the ocean currents. This video shows polyps of a gorgonian (Menella species) capturing food.
Like some other anthozoans, they may form symbiotic relationships with algae called zooxanthellae to supplement nutrition. As well as being nourished by the algae, these gorgonians also receive oxygen produced during photosynthesis.
Gorgonians with symbiotic algae tend to have brownish polyps, while those that only filter feed have brighter colors. They often act as a habitat for other marine animals, for example brittle stars and pygmy seahorses.
Matthew Oldfield is a freelance photographer based in Bali, Indonesia, specializing in editorial and documentary images from both above and below the waves. He works primarily with charities, NGO’s, and other organizations working to conserve the environment, endangered species, and disappearing cultures.
