[1] Its lure apparatus appears to consist of a "complete" fishing rod; the projecting basal bone or pteropterygium being the rod itself; the illicium, a modified dorsal fin ray) being the fishing line; the bioluminescent esca as bait; and hook-like enlarged dermal denticles).

[2] The common names seems to allude to jaw traps; the hinged premaxillae of Lasiognathus resemble the linked jaw-traps employed by trappers to capture large fur-bearing mammals, such as wolves.

Only metamorphosed female Lasiognathus have been collected and described; there is presumably extreme sexual dimorphism in size and shape, as with other deep-sea anglerfishes.

The premaxillaries are separated anteriorly and connected by a broad elastic membrane, and are hinged with the upper jaw so that they are able to flip up and down.

[4] The pterygiophore (the basal bone supporting the illicium) of Lasiognathus is unusually long amongst anglerfish, measuring some 85% of the standard length.

This bone inserts dorsally on the head and is capable of sliding forwards and backwards within a trough that extends the full length of the cranium and between the epaxial musculature on the front half of the body.

[5] The illicium is also long, with a terminal esca and 2-3 bony hook-shaped denticles mounted on an appendage at the tip.

[12] Lasiognathus was first proposed as a monospecific genus in 1925 by the English ichthyologist Charles Tate Regan when he described L. saccostoma,[13] giving its type locality as the Caribbean Sea, approximately 98 km (61 mi) northwest of Negril, Jamaica at 18°50'N, 79°07'W, from a depth of around 2,000 m (6,600 ft).

[14] The closest relative of Lasiognathus is Thaumatichthys, which also has enlarged and hinged premaxillaries, escal denticles, and a branched upper operculum.

However, there are significant differences between those two taxa as well, which include characteristics that Lasiognathus shares with the oneirodids not found in Thaumatichthys.

[16] Stomach contents reveal that Lasiognathus feeds primarily on bony fishes, such as lanternfishes and bristlemouths, and occasionally takes invertebrates including copepods, amphipods, mysid shrimps, siphonophores, salps, pteropods, and chaetognaths.