''Pterygioteuthis giardi'' is a species 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 t ...

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 known as the roundear enope squid. The

specific name Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

honors the

French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...

zoologist and marine biologist Alfred Mathieu Giard (1846-1908). Cephalo

Anatomy and morphology

Squid in the family Pyroteuthidae have Photophores (small, light-producing organs) on viscera (internal organs), stalk of tentacles, and five large and ten small photophores underneath the eyes. The squid has a wide, triangular mantle with a rounded posterior end and rounded fins on the distal dorsal end of the mantle. Their mantles are generally less than 34 mm long. Their tentacles look like bent clubs due to their permanent constriction. Adult squid in the ''Pterygioteuthis'' genera lack hooks on their tentacular clubs, but do have some hooks on the arms. Male squid have a specialized arm used to transfer sperm to females called hectocotyli. Females do not have suckers on their ventral arms and only have one oviduct developed.

Distribution and habitat

Squid in the Pyroteuthidae family live in the mesopelagic (midwater or twilight zone) during the day. At night, they migrate to the epipelagic waters (0-200m). There is little knowledge about the life history of these squid due to the difficulties in studying them, but research on ''P. gemmata'' estimated its maximum age to be 78 days, and it is presumed that others in the Pyroteuthidae family have similar life-spans. Similarly, there is little species-specific information about diet, but in a study of diets of cephalopods in the eastern Gulf of Mexico, it was found that ''P. giardi'' feed on small crustaceans such as copepods. ''P. giardi'' inhabits the Atlantic ocean between 40°N and 34°S and temperate regions (north and south) of the Pacific, but is not found in the eastern tropical Pacific. Off the coast of Hawaii, ''P. giardi'' was found much more abundantly on the leeward (wind-protected) side of the inner boundary zone than the windward zone. Based on data from a study conducted in Hawaii, it was proposed that ''P. giardi'' might be a facultative-boundary species, which means that it can live in the boundary between the mesopelagic and neritic (coastal) zones but does not have to in order to survive. Predators of ''P. giardi'' vary by location but they include some large dolphins and fish. In the south Pacific, a study of the diet of the Guadalupe Fur Seal showed that it also preys on P. giardi.

Behavior

In laboratory experiments, ''P. giardi'' has been observed to produce a luminescent flash when shocked with an electrode. It is likely that the squid use these flashes as a defense against predators. Organisms with photophores often also use luminescent flashes to attract prey or engage in mating rituals. ''P. giardi'' is also able to use

Counter-illumination Counter-illumination is a method of active camouflage seen in marine animals such as firefly squid and midshipman fish, and in military prototypes, producing light to match their backgrounds in both brightness and wavelength. Marine animals of ...

(break up their silhouette with light from photophores) under light conditions similar to those in the upper mesopelagic zone.

Taxonomy

''P. giardi'' is a part of the ''P. giardi'' clade along with ''P. hoylei'', which was originally classified as a subspecies of ''giardi'', but was changed to species classification in 1987. ''P. giardi'' and ''P. hoylei'' are now recognized to be sister species.

Conservation status

''P. giardi'' is listed as a least concern species on the IUCN Red List. However, they list the need for further research into species-specific population size and dynamics, life history, ecology, and threats.

References

External links

Tree of Life web project: ''Pterygioteuthis giardi''Luminescent Flashing in the Midwater Squids ''Pterygioteuthis microlampas'' and ''P. giardi''
{{Taxonbar, from=Q3200292 Pterygioteuthis Cephalopods described in 1896