Pyroteuthis addolux is a species of squid

Squid

Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...

 in the family Pyroteuthidae

Pyroteuthidae

Fire squid are species belonging to the family Pyroteuthidae. The family comprises two genera. Species are diurnally mesopelagic, however migrate into surface waters during the night. The family is characterised by the tentacles, which have a permanent constriction and bend near the base; and...

. It is distinguished from other members of the genus Pyroteuthis

Pyroteuthis

Pyroteuthis is a genus of squid in the family Pyroteuthidae. It is differentiated from the genus Pterygioteuthis by size, head shape and behaviour. Species within the genus are separated by the arrangement of tentacular photophores; the shape of the hectocotylus, and the shape of the hectocotylus...

by the shape of photophore

Photophore

A photophore is a light-emitting organ which appears as luminous spots on various marine animals, including fish and cephalopods. The organ can be simple, or as complex as the human eye; equipped with lenses, shutters, color filters and reflectors...

s on the tentacle

Tentacle

A tentacle or bothrium is one of usually two or more elongated flexible organs present in animals, especially invertebrates. The term may also refer to the hairs of the leaves of some insectivorous plants. Usually, tentacles are used for feeding, feeling and grasping. Anatomically, they work like...

s and the shape of the hectocotylus

Hectocotylus

A hectocotylus is one of the arms of the male of most kinds of cephalopods that is modified in various ways to effect the fertilization of the female's eggs. It is a specialized, extended muscular hydrostat used to store spermatophores, the male gametophore...

. The hectocotylus is located on arm

Cephalopod arm

A cephalopod arm is distinct from a tentacle, though the terms are often used interchangeably.Generally, cephalopod arms have suckers along most of their length, as opposed to tentacles, which have suckers only near their ends. Octopuses have eight arms and no tentacles, while squid and cuttlefish...

 IV, containing 10 proximity hooks, and 6–15 suckers at the tip. The range of P. addolux stretches from south of the Hawaii

Hawaii

Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

an Islands, to the Subantarctic

Subantarctic

The Subantarctic is a region in the southern hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° – 60° south of the Equator. The subantarctic region includes many islands in the southern parts of the Indian Ocean, Atlantic Ocean and...

 boundary. They exhibit minor geographical variance, as southern specimens are slightly smaller than their northern counterparts. P. addolux is the only member of the genus to occur in the North Pacific, however additional members of the family Pyroteuthidae have also been found. The species has been observed using bioluminescence

Bioluminescence

Bioluminescence is the production and emission of light by a living organism. Its name is a hybrid word, originating from the Greek bios for "living" and the Latin lumen "light". Bioluminescence is a naturally occurring form of chemiluminescence where energy is released by a chemical reaction in...

to reduce its silhouette in dim surrounding light.