How to Identify Humpback Blackdevil

To identify Humpback Blackdevil (Melanocetus johnsonii), look at these key features.

Physical Characteristics

Body shape

rounded

Coloration

Uniformly dark brown to black, aiding in camouflage in the deep-sea environment.

Scale type

none

Mouth position

superior

Distinctive features

Globular, somewhat compressed body shape., Large, upward-pointing mouth with numerous long, sharp, recurved teeth., Prominent, bioluminescent lure (esca) at the tip of the illicium (modified first dorsal fin ray) in females., Dwarfed, parasitic males that attach to females., Absence of pelvic fins.

Dorsal fin

Single, short-based dorsal fin located far back on the body, typically with 16-17 rays. The first dorsal fin ray is modified into the illicium and esca.

Tail fin

Rounded caudal fin, typically with 9 rays.

Pectoral fin

Small, paddle-like pectoral fins, typically with 14-18 rays.

Distinctive fins

Anal fin short-based, located opposite the dorsal fin, typically with 13-14 rays. Pelvic fins are absent.

Identification Tips

1. 1

   Bioluminescent Lure (Eska)

   Only present in females, this glowing appendage is the most distinctive feature, used to attract prey in the dark depths. The esca's morphology can vary slightly between species but is generally a simple, bulbous structure.

2. 2

   Body Shape and Coloration

   The Humpback Blackdevil has a characteristic globular, dark body. This combination is typical of many deep-sea anglerfishes but helps distinguish it from other deep-sea fish families.

3. 3

   Mouth and Teeth

   Its large mouth, armed with numerous long, sharp, inward-pointing teeth, is a key predatory adaptation and identification feature.

4. 4

   Sexual Dimorphism

   The extreme size difference between the large female and the tiny, parasitic male is a defining characteristic of the family Melanocetidae and many other deep-sea anglerfishes.

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