A subsequent specimen from the north Atlantic was placed by Regan and Trewavas (1932) into a new genus, Amacrodon, based on differences in dentition.

[2][3] The closest relative of Thaumatichthys is Lasiognathus, which also possesses enlarged, hinged premaxillaries, denticles on the esca, and a branched upper operculum.

[3] Uniquely amongst deep-sea anglerfish, adult Thaumatichthys are benthic in nature; T. binghami and T. pagidostomus are found on the continental shelf between 1,000–2,000 m, while T. axeli is found in the abyssal zone at about 3,600 m.[3] As with most other deep-sea anglerfishes, Thaumatichthys shows extreme sexual dimorphism with the females much larger and different in morphology from the males.

The escal bulb terminates in a pair of forked tendrils and bears varying numbers of lateral lobes and a single curved denticle.

There are numerous black papillae with white tips, resembling those of the lateral line (and likely belonging to the same sensory system), inside the mouth.

The skin is velvet black or dark brown, with numerous small spines on the lower part of the head and body.

[3] The males are small and slender, with greatly enlarged olfactory organs, long hooked denticles at the tips of the jaws, and no esca.

Despite this highly specialized predatory apparatus however, examination of stomach contents revealed sea cucumbers as well as plant matter, suggesting that these fishes are omnivores that will swallow anything edible.