Velvet belly lantern shark, a dogfish shark species named after its velvet-black, bioluminescent belly

The velvet belly lantern shark (Etmopterus spinax) is named after its velvet-black belly [1]. Shorter names for this dogfish shark species are velvet belly or lantern shark. The velvet belly is a cartilaginous fish (order Chondrichthyes). The blue-light-emitting organs are intrinsic photophores, which do not employ luminescent bacteria. Fish-intrinsic bioluminescence of that kind is known to bone fish (order Osteichthyes) , but has until now not been studied in cartilaginous fish [1].

Velvet bellies, with a typical body length of less than two feet, live in deep water of the Atlantic Ocean, preferring the slopes of the outer continental shelves. They have been caught at a depth about 6,000 feet below the water surface. Squids and crabs are their main diet [2].

Velvet belly names in other languages [2]:
German: Schwarzer Dornhai
French: Sagre

Keywords: ichthyology, Etmopteridae, Squaliformes, deep-sea fish, hormone-controlled bioluminescence

References
[1] S. R: Glow in the Shark. Natural History November 2010, Volume 119, Number 2, page 10.
[2] Grzimeks Tierleben • Vierter Band • Fische 1, page 122 and 516.