''Pyroteuthis'' is a genus of

squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting ...

in the family

Pyroteuthidae Pyroteuthidae (the fire squids) is a family of squids. The family comprises two genera. Species are diurnally mesopelagic, migrating into surface waters during the night. The family is characterised by the tentacles, which have a permanent con ...

. It is differentiated from the genus ''

Pterygioteuthis ''Pterygioteuthis'' is a genus of squid in the family Pyroteuthidae. Members are differentiated from the genus ''Pyroteuthis ''Pyroteuthis'' is a genus of squid in the family Pyroteuthidae. It is differentiated from the genus '' Pterygioteuth ...

'' by size, head shape and behaviour. Species within the genus are separated by the arrangement of tentacular

photophores A photophore is a glandular organ that 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, h ...

; the shape of the

hectocotylus A hectocotylus (plural: ''hectocotyli'') is one of the arms of male cephalopod A cephalopod is any member of the molluscan class Cephalopoda ( Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusive ...

, and the shape of the hectocotylus hooks. With the exception of the

Tropical Eastern Pacific The Tropical Eastern Pacific is one of the twelve marine realms that cover the coastal waters and continental shelves of the world's oceans. The Tropical Eastern Pacific extends along the Pacific Coast of the Americas, from the southern tip of t ...

, the genus is circumpolar in tropical and temperate oceans. The species '' P. addolux'' is the only member to occur in the

North Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

References

External links

Tree of Life web project: ''Pyroteuthis''
Pyroteuthidae Cephalopod genera Bioluminescent molluscs Taxa named by William Evans Hoyle {{squid-stub