The belligerent sculpin was first formally described in 1814 as Cottus platycephalus by the German zoologist Peter Simon Pallas with its type locality given as Kamchatka and the Sea of Okhotsk.

[2] In 1861 the American biologist Theodore Gill classified this species in the monospecific genus Megalocottus.

[6] The belligerent sculpin has a broad, strongly flattened head, much wider than it is deep with a projecting lower jaw.

The top and the sides of the head are very warty and there are large spines or bumps behind the eye and on the nape, these may have short cirri on them.

The juveniles feed on algae, and crustaceans such as copepods, cumaceans, amphipods, and mysids while the adults have a similar diet but they also eat small fishes.