see text Leftvents are a family, the Linophrynidae, of marine ray-finned fishes which is classified within the suborder Ceratioidei, the deep sea anglerfishes.

The leftvent family, Linophrynidae, was first proposed in 1926 by the English ichthyologist Charles Tate Regan as a monotypic family when he was describing specimens of previously unknown species of ceratioid fishes collected from the North Atlantic, the Caribbean Sea and the Gulf of Panama from the Danish reaearch ship,Dana.

The prefix may be a reference to the sac like mouth hanging off the trunk, which in the holotype contained a lanternfish, like a fisherman's keep net.

Its use may date as far back as Aristotle and Cicero, who referred to anglerfishes as "fishing-frogs" and "sea-frogs," respectively, possibly because of their resemblance to frogs and toads.

Metamorphosed females are typically dark brown to black, although the appendages of the esca, the parts of the bulb of the esca close to the tip and the hyoid barbel of Linophryne, and the fin rays have no pigmentation, with the exception of fishes in the genus Haplophryne.

[7] The metamprphosed males have very large forward pointing, rather tubular eyes with diameters that are equivalent to between 6% and 9% of the standard length.

The parasitic males have denticular teeth, while their eyes, and olfactory organs degenerate and they have very inflated bellies.

Its circulatory system becomes fused with the female's, and from the point of union the male receives all its nutrients through the joined blood circulation.

This strategy evolved to ensure that the spawn is fertilised in the sparsely populated habiata of these deepwater anglerfishes.