''Lampadioteuthis megaleia'' is a small, colorful

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 t ...

from the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Lycoteuthidae The Lycoteuthidae are a family of squid comprising four known genera in two subfamilies. They are small muscular squid characterised by a lack of hooks and by photophores present on the viscera, eyeballs and tentacles. They inhabit tropical an ...

, it is the only species in the only genus in the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispec ...

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...

Lampadioteuthinae, it is sometimes known as the wonderful firefly squid. It differs from the other species of the Lycoteuthidae mainly by having a

hectocotylus A hectocotylus (plural: ''hectocotyli'') is one of the arms of male cephalopods that is specialized to store and transfer spermatophores to the female. Structurally, hectocotyli are muscular hydrostats. Depending on the species, the male may use i ...

in the males and by the possession of a rostrum on the

gladius ''Gladius'' () is a Latin word meaning "sword" (of any type), but in its narrow sense it refers to the sword of ancient Roman foot soldiers. Early ancient Roman swords were similar to those of the Greeks, called '' xiphe'' (plural; singular ''xi ...

Description

''Lampadioteuthis megaleia'' is a small squid which grows to a mantle length of 40 mm. In males the right ventral

arm In human anatomy, the arm refers to the upper limb in common usage, although academically the term specifically means the upper arm between the glenohumeral joint (shoulder joint) and the elbow joint. The distal part of the upper limb between the ...

is hectocotylized with an enlarged protective membrane over the mid-arm. It has four ocular

photophore 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, ...

s, arranged as three in a

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. Th ...

line and one positioned laterally. The

tentacles In zoology, a tentacle is a flexible, mobile, and elongated organ present in some species of animals, most of them invertebrates. In animal anatomy, tentacles usually occur in one or more pairs. Anatomically, the tentacles of animals work main ...

have five photophores which are set on a stalk. There are circular anal photophores on either side of the

rectum The rectum is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the s ...

, single elongated branchial photophores lie at the base of each gill, there are no abdominal photophores and a single photophore is situated to the rear of the abdomen between the inner surface of mantle and the

viscera In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a ...

. There are a lot of functional

chromatophores Chromatophores are cells that produce color, of which many types are Biological pigment, pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and ...

which are covered by a violet pigmented external skin. The males have a penis.

Distribution

''Lampadioteuthis megaleia'' occurs in the subtropical North Atlantic Ocean in the

Gulf Stream The Gulf Stream, together with its northern extension the North Atlantic Current, North Atlantic Drift, is a warm and swift Atlantic Ocean, Atlantic ocean current that originates in the Gulf of Mexico and flows through the Straits of Florida a ...

and the northern

Sargasso Sea The Sargasso Sea () is a region of the Atlantic Ocean bounded by four currents forming an ocean gyre. Unlike all other regions called seas, it has no land boundaries. It is distinguished from other parts of the Atlantic Ocean by its charac ...

and in the southwestern Pacific Ocean. Its type locality is the

Kermadec Islands The Kermadec Islands ( mi, Rangitāhua) are a subtropical island arc in the South Pacific Ocean northeast of New Zealand's North Island, and a similar distance southwest of Tonga. The islands are part of New Zealand. They are in total are ...

, in the South Pacific Ocean, In the eastern North Atlantic it has been reported from between the

Azores ) , motto =( en, "Rather die free than subjected in peace") , anthem= ( en, "Anthem of the Azores") , image_map=Locator_map_of_Azores_in_EU.svg , map_alt=Location of the Azores within the European Union , map_caption=Location of the Azores wi ...

and Spain south to 25°N while in the western North Atlantic it has been recorded at 40°N.

Habitat and biology

''Lampadioteuthis megaleia'' is found in the upper

mesopelagic The mesopelagic zone (Greek μέσον, middle), also known as the middle pelagic or twilight zone, is the part of the pelagic zone that lies between the photic epipelagic and the aphotic bathypelagic zones. It is defined by light, and begins ...

epipelagic The photic zone, euphotic zone, epipelagic zone, or sunlight zone is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological proc ...

zones. Little is known about its life history but the violet pigmentation in the skin lying over its photophores is assumed to act as a colour filter which enables the

bioluminescence Bioluminescence is the production and emission of light by living organisms. It is a form of chemiluminescence. Bioluminescence occurs widely in marine vertebrates and invertebrates, as well as in some fungi, microorganisms including some b ...

to be a closer match to the colour of the sun or moonlight downwelling from the surface. The photophores of species of squid in the genus ''

Lycoteuthis ''Lycoteuthis'' is a genus containing two species of squid: '' Lycoteuthis springeri'' and ''Lycoteuthis lorigera''. They are small animals which grow up to 8 cm in length. These squid live in the deep sea at depths of up to 3000 metres, m ...

'' have a very similar type of detached filter. Small, less than 8mm in mantle length, subadults have been found which are very similar to adults, except that some of the body proportions differ, the size of the photophores and only having the large photophore at the base of each tentacle. The

paralarva Paralarvae (singular: ''paralarva'') are young cephalopods in the planktonic stages between hatchling and subadult. This stage differs from the larval stage of animals that undergo true metamorphosis. Paralarvae have been observed only in membe ...

are

planktonic Plankton are the diverse collection of organisms found in water (or air) that are unable to propel themselves against a current (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucia ...

References

{{Taxonbar, from=Q3201562 Squid Cephalopod genera Molluscs described in 1916 Monotypic mollusc genera Bioluminescent molluscs