The Blackbelly lanternshark or Lucifer shark, Etmopterus lucifer, is a shark of the family Dalatiidae, found circumglobally in tropical, subtropical and temperate seas, at depths of between 492.13 and 4101.05 ft (150 and 1,250 m). Its length is up to 18.5 in (47 cm).
The Blackbelly lanternshark has a pointed, slightly upturned snout and a spine in front of each of two dorsal fins the second of which is larger than the first. The pelvic fins are also larger than the pectorals. Dermal denticles shaped like curving erect spines are arranged in conspicuous longitudinal rows. The upper jaw teeth are separate and sharply pointed – the lower are set broad and overlapping to form a continuous cutting edge.
The belly is black and contains a dense array of small photophores emitting green light. The flanks and back are dark grey and there is an abrupt color division with the black underside.
They feed on squid, small bony fish and shrimp.
Blackbelly lanternsharks are ovoviviparous.
Illustration by Dr Tony Ayling