I am a big fan of sea fans! Why won’t anyone be, considering their wonderful shapes and colours? They are found amongst the reefs of the Indo-Pacific oceans, and make some of the most beautiful underwater sights. Sea fans are actually colonies of lots of small, individual polyps, similar to corals. Some form colonies in a single sheet, while others grow their branches in somewhat of a tangle. They particularly like areas where there is strong water current, building colonies in branching formations that are almost always fan-shaped, hence the common name.
While SCUBA diving on the reef sighting a sea fan is not difficult. A fun bit of searching can give you a closer look at the astonishing beauty of these life forms. They are commonly found in areas where there is strong current: reef slope, or jutting out from drop-offs or steep banks in locations where currents sweep plankton and other organic nutrients across the polyps’ tentacles.
Shapes and sizes
Naturally they occur in an array of colours, most of which actually are the result of tiny algae that live in the structural tissue of the Gorgonian. Beyond giving them attractive colouration, these tiny algae called ‘Zooxanthellae’ also produce nutrients through photosynthesis—a process through which plant-algae and bacteria make their own food, using light from the sun and carbon dioxide and water—which benefits the sea fan. In addition to providing home for algae, sea fans also provide home and structure for a variety of juvenile fishes, shrimps, feather stars and clamshells.
Most sea fans grow up to a few inches, but at some locations their flare grows up to a meter or so in width and when they sway with the current their beauty is nothing less than seeing the dancing peacock on land. Some form colonies in a single plane, while others grow their branches in somewhat of a tangle. Unlike corals, which has six tentacles (Hexacorals) sea fans are Octocorals: each polyp has eight tentacles, which it uses to capture suspended nutrients in the water column.
It is not that all Gorgonians form fanciful sea fan shaped colonies. Some families have long, slender colonies known as sea whips. They jut out from the sea bottom like branches of trees, which makes them easy to distinguish from the sea fan. Due to their gentle swaying they are a favourite subject of photography amongst divers. India has rich diversity of sea fan. A total of 103 species are known to occur in our waters. They are classified into 4 common types, Black, Red, Flower and Monkey tail.Their beauty is at its peak when they are alive and on uprooting they lose their colouration and shape. Due to their high demand in illegal trade, today they are endangered in many reefscapes. Apart from species samples present in Government run zoos, aquariums and educational institutions no regulated trade of sea fans is allowed. From 2001 the Indian law has given the sea fans the strictest form of legal protection, which means collecting, possessing or handling sea fans can give you upmto 25,000 rupees of fine or three years in prison or in some cases both.
Yet, sea fans are exploited and sold in aquarium markets. The value of single piece of sea fan can go up to several dollars. With sustained efforts and continuous support from the Government, the trade of sea fans can reduce and these beautiful life forms will be allowed to live in peace, as they have for millennia before us. After all, wouldn’t you like to see a sea fan when you have a chance to visit a coral reef?
Sea fans are also called ‘Gorgonians’. In Greek mythology, the Gorgons were three sisters whose hair was made of living snakes.
Within phylum Cnidaria, class Anthozoa, sea fans belong to the order Alcyonacea.
They are closely related to corals, however unlike corals, which have six tentacles (and are therefore called Hexacorals), sea fans are Octocorals, with eight tentacles to a polyp. The tentacles capture suspended micro-organisms in the water column: yummy!
A total of 103 species of sea fans are known to occur in Indian waters. They are divided into four common types: Black, Red, Flower and Monkey-tail sea fans.