New Lanternshark Species Among the World’s Smallest Sharks

Off the coasts of Mauritius, in the southwest Indian Ocean, biologists have discovered a new shark species as tiny as it is discreet: the bulb-nosed lanternshark.

Etmopterus bulbosus

Described in the Journal of the Ocean Science Foundation, E. bulbosus features a prominent bulbous nose that largely distinguishes it from the other 42 lanternshark species in the genus Etmopterus. Scientists also note skin denticles at the base of the pectoral fin, a structure similar to that of E. sentosus.

This new shark was described from a single female specimen, captured at a depth of about 450 meters. With a total length not exceeding 21.5 centimeters, it can almost fit in the palm of a hand and is only slightly larger than the smallest known shark, Etmopterus perryi, which does not exceed 21.2 centimeters in adulthood.

Like other lanternsharks, E. bulbosus is carnivorous. Its upper teeth, equipped with sharp points called cuspids, differ markedly from those lining its lower jaw, which resemble blades.

With a dark purplish coloration, its skin is covered with photophores, tiny light-emitting organs observed in many species of the Etmopterus genus. While the ecology of their most recently described member remains unclear at this stage, this type of bioluminescence is closely tied to prey search as well as to defense against predators.

Des requins relativement épargnés

Currently, the International Union for Conservation of Nature (IUCN) has assessed 40 of the 43 Etmopterus species, with 36 regarded as of least concern and a single one listed as vulnerable.

A situation closely tied to the depth at which these sharks inhabit, typically deeper than the zones where trawling occurs.

Previously, it was a new walking shark species that had been discovered in Papua New Guinea.