Ogcocephalus vespertilio was first formally described as Lophius vespsertilio by Carl Linnaeus in the 10th edition of Systema Naturae with its type locality given as the "American Ocean".

[5] The family Ogcocephalidae is classified in the monotypic suborder Ogcocephaloidei within the order Lophiiformes, the anglerfishes in the 5th edition of Fishes of the World.

The flattened head and body of this fish, thee "disc" is made up of the head and the body as far as the axilla of the pelvic fins, the forward edge of the disc is made up of the extended bones of the operculum sweeping backwards from the cranium and surrounding the trunk on either side.

Thee small dorsal and anal fins are covered in skin and are located on the upper and lower surfaces of the tail.

In preserved specimens the overall colour on the upper parts is brown marked with dark spots with pale lines between them.

It occurs at depths between 24 and 66 m (79 and 217 ft) on soft substrates on the continental shelf, even entering the lower parts of estuaries.

[1] Here is a remarkable instance of a specimen of this species being found in pure freshwater between 1,300 and 1,400 km (810 and 870 mi) upstream from the mouth of the Amazon.