Humpback angler

The humpback angler, Melanocetus johnsonii, is a black seadevil of the family Melanocetidae, found in tropical to temperate parts of all oceans at depths of up to 2,000 m. Its length is up to 3 cm for males and up to 20 cm for females.

Female humpback anglers have an enormous head dominated by a cavernous mouth full of long slender teeth that can fold backwards when prey is being swallowed. The belly is distensible and this, along with the huge gape of the mouth, allows them to swallow fishes up to twice their own length. Their eyes are small and covered by a thin layer of skin, and between them arises a large lure which is actually a modified first dorsal fin ray. (Wikipedia)