The kitefin shark, the largest luminous vertebrate on record,[3] has a slender body with a very short, blunt snout, large eyes, and thick lips.

The low reproductive rate of this species renders it susceptible to overfishing and, coupled with known population declines, has led it to be assessed as Vulnerable by the International Union for Conservation of Nature (IUCN).

The kitefin shark was originally described as Squalus licha by French naturalist Pierre Joseph Bonnaterre, in his 1788 Tableau encyclopédique et méthodique des trois regnes de la nature; the type specimen from "Le cap Breton" has since been lost.

[8][9] Dalatias and Isistius are believed to have evolutionarily diverged shortly after the transition between the Cretaceous and Tertiary periods (65.5 Ma), as part of a larger adaptive radiation of dogfish sharks from the deep sea into relatively shallower habitats.

[8] The oldest fossil teeth that definitively belong to the kitefin shark date to the Middle Eocene epoch, such as those recovered from Bortonian-stage deposits (43.0–37.0 Ma) in New Zealand.

[11] An 90 cm (3.0 ft) long kitefin shark with partial albinism, lacking pigment on 59% of its body, was caught in the Gulf of Genoa in 2003.

Unlike in a previous case of an albino Portuguese dogfish, the abnormal coloration of this individual had not diminished its ability to capture prey.

[16] The kitefin shark has an almost circumglobal range in tropical and warm-temperature waters, consisting of a number of widely separated populations with likely little interchange between them.

[10] It is the only member of its family that tends to be found close to the sea floor as opposed to in the middle of the water column, though on occasion it has been captured well above the bottom.

[18] It is a slow swimmer with a large liver filled with squalene, a lipid less dense than water, allowing it to maintain neutral buoyancy and hover above the bottom with little effort.

[21] A powerful and versatile deepwater predator, the short, robust jaws of the kitefin shark give it an enormously strong bite.

[18][22] The presence of fast-swimming fishes in its diet suggests the kitefin shark may scavenge, or have some other means of capturing faster prey.

[4] Reproduction in the kitefin shark is aplacental viviparous, with the embryos hatching inside the uterus and being sustained to term by yolk.

[22] This species has a long history of human exploitation: the meat is consumed in the eastern Atlantic and Japan, and the offal processed into fishmeal.

The skin is made into a type of shagreen useful in the making of furniture and jewelry, and is also favored for the manufacture of "boroso", a Spanish polished leather.

In the early 1980s, the fishing fleet was enlarged with the addition of industrial vessels equipped with demersal gillnets, resulting in a fishery peak in 1984 of 937 tons landed.

After 1991, kitefin shark catches declined precipitously to under 15 tons annually which, along with a drop in the global price of liver oil, led to the fishery becoming unprofitable by the end of the decade.

[24][25] Fisheries operating off Portugal and Japan are responsible for most commercial landings of the kitefin shark, generally as bycatch in bottom trawls and on hook-and-line.

[27] The International Union for Conservation of Nature has assessed the kitefin shark as a vulnerable species in light of documented population declines.