Krøyer’s deep sea angler fish

The Krøyer’s deep sea angler fish, Ceratias holboelli, is a seadevil of the genus Ceratias, found in all oceans, at depths of from 0.62 to 1.24 mi (1,000 to 2,000 m). Its length is from 19.69 to 29.53 in (50 to 75 cm).

The Krøyer’s deep sea angler fish is larger than most other deepwater anglerfish, however half of this length is taken up with a long filamentous rayed tail. These fishes have round flabby bodies with a soft fibrous skeleton and prickly skin. Like most other deepwater anglerfish this fish has a small eye, no pelvic fins and is colored black. It has a moderately sized mouth and the fishing lure on top of the head is as long as the body and topped by a small luminous bulb. Between the lure and the dorsal fin is another thin filament about half the length of the lure.

Males are free swimming when young but before they mature these small fishes (about a tenth the size of the female) attach themselves permanently to the hind body of the female and become parasitic. Their blood supply becomes continuous with that of the female and most of the internal organs degenerate: they become simply appendages to supply sperm when required.