What is a Tripod Fish?

The tripod fish is so-called because it has three leg-like projections which extend from its fins. It uses all three of them to stand on the sea bed in a tripod-like fashion. These elongated fins also mean that it is called a 'stilt walker' fish as it uses them to feel its way along, often in very low light conditions. A type of benthic fish, the species inhabits the floor of the ocean throughout its life cycle. It tends to prefer temperate and tropical waters and can be found in the Atlantic, the Pacific and the Indian Ocean.

The tripod fish is relatively small creature. Their body length is commonly in the region of 30 cm but they have been measured larger than that with the very biggest ones extending to about 37 cm in length. When the fish's elongated fins are also taken into account they can measure well over three feet in length, or about one metre. They vary in colour over their bodies. Light brown and bronze tones can be found which fades to grey over the fishes' undersides, lower backs and heads.

In terms of their physiology, tripod fish possess remarkably modified pelvic and caudal fins. These have the aforementioned elongations at their tips, which are referred to as either rays or elements. The extremely lengthy rays, which protrude from the pelvic fins are known to be rigid at times but not at others. The same phenomenon has also been noted with the ray that extends from the tail or lower caudal fin. The rigidity shown in these rays tends to occur when the fish rests over the ocean floor for the purposes of feeding. Nonetheless, the fish's three rays appear to be perfectly flexible in the water when the animal decides that it is time to swim on to a new location. Furthermore, tripod fish use their pectoral fins as tactile organs to sense prey. Like some other species of fish, they extend them up above their bodies to detect prey, just like antennae.

Tripod fish are inhabitants of the abyssal zone, living on the sea bed at a depth of anywhere between 3,000 to 15,000 feet. Because of this great depth, much has still to be learned about the species. In addition, its chosen habitat means that it does not come into contact from humans very often and it is subsequently not considered to be an endangered species. Another result of their deep environment is that their eyes have become very tiny. Indeed, their capacity for vision has almost disappeared due to the dark of the deep ocean where the ability to see well is of little value.

Solitary animals, these fish are thought to stand on their rays just above the substrate where there is more current in order to hunt by allowing prey to come to it. Since this method of catching planktonic crustaceans and zooplankton requires very little energy, it is able to eke out an existence as a predator in the near freezing waters and high pressure, not to mention the darkness, of the deep ocean. The species is known to be hermaphroditic, which means that they possess male and female reproductive organs. Should an individual fish not be able to locate a potential mate - often a result of its solitary existence - then it is able to fertilize its own eggs.