Moroteuthopsis ingens, the greater hooked squid, is a species of squid in the family Onychoteuthidae. It occurs worldwide in subantarctic oceans.
Taxonomy M. ingens was long attributed to the genus Moroteuthis, which became a junior synonym of Onykia in 2010; this species was subsequently lumped into that genus, though it was separated from all other Onykia spp. into its own subgenus; Moroteuthopsis.Bolstad, K.S.R. 2010. Systematics of the Onychoteuthidae Gray, 1847 (Cephalopoda: Oegopsida). Zootaxa 2696: 1–186. Preview A 2018 study of mitochondrial DNA of the family Onychoteuthidae subsequently found that the subgenus Moroteuthopsis was deemed distinct from the rest of Onykia, and furthermore, this species formed a monophyletic clade with Kondakovia longimana. Thus, it was decided to elevate subgenus Moroteuthopsis into a full genus, and this species became its type species by seniority, with "K." longimana becoming the second species in Moroteuthopsis.
Biology Size and growth The size of a fully grown M. ingens including the clubbed tentacles is currently unknown. Many estimates, however, predict that the mantle may reach lengths of up to . Research has found that egg sizes of the squid average 2.1 mm inside mature females, while juveniles average or larger. Juveniles are presumed to live near the surface, until they reach a mantle length of approximately , at which time they relocate to deeper water, and larger prey. M. ingens exhibit sexual dimorphism, with females growing linearly twice as fast as males, and reaching a fully mature weight of more than five times that of male counterparts.Bolstad, K. 2003. Spotlight on: Moroteuthis ingens . The Octopus News Magazine Online.
Penis elongation has been observed in this species; when erect, the penis may be as long as the mantle, head and arms combined.Arkhipkin, A.I. & V.V. Laptikhovsky 2010. Observation of penis elongation in Onykia ingens: implications for spermatophore transfer in deep-water squid. Journal of Molluscan Studies, published online on June 30, 2010. Walker, M. 2010. Super squid sex organ discovered. BBC Earth News, July 7, 2010. As such, deep water squid like M. ingens have the greatest known penis length relative to body size of all mobile animals, second in the entire animal kingdom only to certain sessile barnacles.
Ecology It is generally accepted that there are large dietary variations between large and small M. ingens. One of the most common findings is that juvenile squid (>200 mm ML) consume a greater percentage of crustaceans and cephalopods compared to their size than mature squid, which consume a large percentage of fish and virtually no crustaceans.Phillips, K., P. Nichols & G. Jackson 2003. Size-related dietary changes observed in the squid Moroteuthis ingens at the Argentines Islands: stomach contents and fatty-acid analyses. Polar Biology 26(7): 474-485. Myctophid lantern fish are seen as common prey, globally.Phillips, K., P. Nichols & G. Jackson 2003. Dietary variation of the squid Moroteuthis ingens at four sites in the Southern Ocean: stomach contents, lipid and fatty acid profiles. Journal of the Marine Biological Association of the UK 83: 523-534. Larger squid are known to practice cannibalism (accounting for up to 6% of diet).Cherel, Y. & G. Duhamel 2003. Diet of the squid Moroteuthis ingens (Teuthoidea: Onychoteuthidae) in the upper slope waters of the Kerguelen Islands. Marine Ecology Progress Series 250: 197–203.
M. ingens, as with many (if not all) large squid, has a number of predators. These include the patagonian toothfish, king penguin, wandering albatross, pilot whale, bottlenose whale, dwarf sperm whale, sperm whale, and other types of squid.CephBase: Predators of Moroteuthis ingens . Other predators include Antarctic and Subantarctic fur seals.
References
External links
Tree of Life web project: Onykia ingens First observation of a double tentacle bifurcation in cephalopods