The Mastigoteuthidae, also known as whip-lash squid, are a family of small deep-sea squid. Approximately 20 known species in six genera are represented, with members found in both the

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 at ...

and bathypelagic zone of most oceans. Originally described by Verill in 1881, it was later lowered by Chun (1920) to a subfamily (Mastigoteuthinae) of the

Chiroteuthidae The Chiroteuthidae are a family of deep-sea squid, generally small to medium in size, rather soft and gelatinous, and slow moving. They are found in most temperate and tropical oceans, but are known primarily from the North Atlantic, North Pac ...

. However, Roper et al. (1969) raised it back to the family level, and this has not been changed since. The taxonomy of this family is extremely unstable, and there have been at times one genus (

Young Young may refer to: * Offspring, the product of reproduction of a new organism produced by one or more parents * Youth, the time of life when one is young, often meaning the time between childhood and adulthood Music * The Young, an American roc ...

, Lindgren, & Vecchione, 2008), two genera and four subgenera(Salcedo-Vargas & Okutani, 1994), two genera and several 'groups' (Salcedo-Vargas, 1997), five genera (Braid, McBride, & Bolstad, 2014) and one species with an uncertain placement, or six genera (Young, Vecchione, & Braid, 2014).

Description

Mastigoteuthids range in size from quite small species in the genus '' Mastigoteuthis'', to relatively gigantic sizes in the genus '' Idioteuthis''. However most are rather small, from 3–15 centimetres total mantle length. Their most distinctive features are their extremely elongate

tentacle 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 ma ...

s—which retract into membranous lateral sheaths of the fourth (and largest)

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 th ...

s—and their very large ovate fins, which may occupy up to 80% of the mantle length in some species. It is from these 'whip-like' tentacles that their common name derives. Unlike most other squid, the club of the mastigoteuthid tentacle is not significantly (usually not at all) broader than the rest of the tentacle and is covered in very small suckers—in some species, invisible to the naked eye—which impart an extremely sticky property to the clubs, themselves answering for 70% or more of the tentacle's length in some species. Ventouse calmar

Many species also possess

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 ( bioluminescent organs) which may be located on either the skin, the surface of the eyeball, or the eyelid. These photophores have a "lens" of

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

s, pigment cells which may allow the squid to modify the colour of the light produced by the photophores. The mantle of some species is adorned with conical or hemispherical tubercles. Most species have arm suckers that possess sharp or blunt conical teeth, which are either larger or present only on the distal side, however some species, such as '' Mastigoteuthis inermis'', have smooth sucker rings with no teeth at all (however, the validity of this species is uncertain at the present time). Coloration is typically a rich reddish brown or dark purple. Species in the genus '' Echinoteuthis'' and '' Idioteuthis'' are known to have expanded tentacular clubs as paralarvae (for both species) or adults (''Idioteuthis'').

Behaviour

Members of this family have scarcely been observed in life, but at least two species ('' Mastigopsis hjorti'' and '' Magnoteuthis magna'') are known to hover above the ocean bottom in a vertical orientation, the head pointing downward. The squid use their large fins to maintain this orientation and use both their extended tentacles like fly paper, held rigidly at a constant distance apart: this has been termed the "tuning fork" position. Prey items apparently consist primarily of benthic

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group can ...

s. Although mastigoteuthids possess

ink Ink is a gel, sol, or solution that contains at least one colorant, such as a dye or pigment, and is used to color a surface to produce an image, text, or design. Ink is used for drawing or writing with a pen, brush, reed pen, or quill. Thicker ...

sacs (which could suggest forays into shallower, lit waters), all observations have been over the bottom in deep water. Deep-sea squids commonly possess ink. The squid seem to lack the ability of rapid jet propulsion and instead rely on their large fins.

Species

This family is taxonomically little understood, but there have many recent advances in its systematics. With many species represented by single, damaged, and juvenile specimens, this group is still creating controversy in the taxonomic community. Salcedo-Vargas and Okutani (1994) reclassified the family and eliminated the genus ''Echinoteuthis'', added two subgenera, and reduced the number of species to eight. Three years later, after the careful examination of skin tubercles and photophores, Salcedo-Vargas eliminated his subgenera, and increased the number of species to 17 (Salcedo-Vargas, 1997). Mastigoteuthis glaukopis

According to the

World Register of Marine Species The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive list of names of marine organisms. Content The content of the registry is edited and maintained by scientific specialis ...

the classification of the Mastigoteuthidae is: * Genus '' Echinoteuthis'' Joubin, 1933 **'' Echinoteuthis atlantica'' (Joubin, 1933) **'' Echinoteuthis danae'' Joubin, 1933 **'' Echinoteuthis famelica'' ( Berry, 1909) *Genus '' Idioteuthis'' Sasaki, 1916 **'' Idioteuthis latipinna'' * Sasaki, 1916 **'' Idioteuthis cordiformis'' ( Chun, 1908) *Genus '' Magnoteuthis'' Salcedo-Vargas & Okutani, 1994 **'' Magnoteuthis magna'' (Joubin, 1913) **'' Magnoteuthis microlucens'' (Young, Lindgren & Vecchione, 2008) **'' Magnoteuthis osheai'' Braid & Bolstad, 2015 *Genus '' Mastigopsis'' Grimpe, 1922 **'' Mastigopsis hjorti'' (Chun, 1913) *Genus '' Mastigoteuthis'' **'' Mastigoteuthis agassizii'' Verrill, 1881 **'' Mastigoteuthis dentata'' Hoyle, 1904 **'' Mastigoteuthis flammea'' Chun, 1908 **'' Mastigoteuthis glaukopis'' Chun, 1908 **'' Mastigoteuthis grimaldii'' (Joubin, 1895) **'' Mastigoteuthis psychrophila'' Nesis, 1977 **'' Mastigoteuthis schmidti'' Degner, 1925 **'' Mastigoteuthis hastula'' * (Berry, 1920) **'' Mastigoteuthis inermis'' * Rancurel, 1972 **'' Mastigoteuthis iselini'' * MacDonald & Clench, 1934 **'' Mastigoteuthis latipinna'' * (Sasaki, 1916) **'' Mastigoteuthis okutanii'' * Salcedo-Vargas, 1997 **'' Mastigoteuthis tyroi'' * Salcedo-Vargas, 1997 *Genus '' Mastigotragus'' **'' Mastigotragus pyrodes'' (Young, 1972) The taxa listed above with an asterisk (*) are ''

taxon inquirendum In biological classification, a ''species inquirenda'' is a species of doubtful identity requiring further investigation. The use of the term in English-language biological literature dates back to at least the early nineteenth century. The term t ...

'' and needs further study to determine if it is a valid taxon or a synonym. The validity of several species remains to be reviewed, and the placement of the species '' Mastigotragus pyrodes'' in a separate genus should be assessed with genetics.

References

External links

Tree of Life web project: MastigoteuthidaeMastigoteuthidae discussion forum at TONMO.com
{{DEFAULTSORT:Whip-Lash Squid Squid Bioluminescent molluscs