The Ipnopidae (deepsea tripod fishes) are a family of fishes in the order

Aulopiformes Aulopiformes is a diverse order of marine ray-finned fish consisting of some 15 extant and several prehistoric families with about 45 genera and over 230 species. The common names grinners, lizardfishes and allies, or aulopiforms are sometimes ...

. They are small, slender fishes, with maximum length ranging from about . They are found in temperate and tropical deep waters of the

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the "Old World" of Africa, Europe an ...

, Indian, and

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the contine ...

s. A number of species, especially in the genus '' Bathypterois'', have elongated pectoral and

pelvic fin Pelvic fins or ventral fins are paired fins located on the ventral surface of fish. The paired pelvic fins are homologous to the hindlimbs of tetrapods. Structure and function Structure In actinopterygians, the pelvic fin consists of two e ...

s. In the case of the tripodfish, ''

Bathypterois grallator The tripodfish or tripod spiderfish, ''Bathypterois grallator'', is a deep-sea benthic fish in the family Ipnopidae found at lower latitudes. It is now relatively well known from photographs and submersible observations, and seems to prefer to p ...

'', these fins are three times as long as the body — up to a meter in length — and are used for standing on the sea floor. Ipnopids either have tiny eyes, or very large eyes that lack any

lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'' ...

; in either case they have very poor vision and are unable to form an image. Ipnopidae is a species of fish that have adapted to living in the deep. Their skeleton is flatter with reinforced bony heads on its fin rays and its pelvic fins are located through the tips of the pectoral fin rays.“Tripod Fish.” Nature (London), vol. 240, no. 5379, 1972, pp. 284–284.

References

* Taxa named by Theodore Gill Ray-finned fish families {{Aulopiformes-stub