''Moroteuthopsis ingens'', the greater hooked squid, is a species of

squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...

in the family

Onychoteuthidae The hooked squid, family (biology), family Onychoteuthidae, currently comprise about 20–25 species (several known from only single life stages and thus unconfirmed), in six or seven genus, genera. They range in mature mantle (mollusc), mantle l ...

. It occurs worldwide in

subantarctic The sub-Antarctic zone is a physiographic region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46th parallel south, 46° and 60th parallel south, 60° south of t ...

oceans.

Taxonomy

''M. ingens'' was long attributed to the genus ''Moroteuthis'', which became a

junior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...

of ''

Onykia ''Onykia'' is a genus of squids in the family Onychoteuthidae. Due to similarities between the genera, several recent authors consider the genus ''Moroteuthis'' a junior synonym of ''Onykia''. The type species is '' Onykia carriboea'', the tropic ...

'' in 2010; this species was subsequently lumped into that genus, though it was separated from all other ''Onykia spp.'' into its own

subgenus In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

; ''

Moroteuthopsis ''Moroteuthopsis'' is a genus of squid in the family Onychoteuthidae. The type species is ''Moroteuthopsis ingens''. Prior to 2018, ''Moroteuthopsis'' was considered a subgenus of ''Onykia''; after the mitochondrial DNA of the family Onychoteuthi ...

''. A 2018 study of

mitochondrial DNA Mitochondrial DNA (mtDNA and mDNA) is the DNA located in the mitochondrion, mitochondria organelles in a eukaryotic cell that converts chemical energy from food into adenosine triphosphate (ATP). Mitochondrial DNA is a small portion of the D ...

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 In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

clade with ''

Kondakovia longimana ''Moroteuthopsis longimana'', previously ''Kondakovia longimana'', the giant warty squid or longarm octopus squid (though it is not a true octopus squid),O'Shea, S. 2005''Kondakovia longimana'' In: Giant Squid and Colossal Squid Fact Sheet. The O ...

''. 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 Sexual dimorphism is the condition where sexes of the same species exhibit different Morphology (biology), morphological characteristics, including characteristics not directly involved in reproduction. The condition occurs in most dioecy, di ...

, with females growing linearly twice as fast as males, and reaching a fully mature weight of more than five times that of male counterparts.

Penis A penis (; : penises or penes) is a sex organ through which male and hermaphrodite animals expel semen during copulation (zoology), copulation, and through which male placental mammals and marsupials also Urination, urinate. The term ''pen ...

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. 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

barnacle Barnacles are arthropods of the subclass (taxonomy), subclass Cirripedia in the subphylum Crustacean, Crustacea. They are related to crabs and lobsters, with similar Nauplius (larva), nauplius larvae. Barnacles are exclusively marine invertebra ...

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

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s and

cephalopod A cephalopod is any member of the molluscan Taxonomic rank, class Cephalopoda (Greek language, Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral symm ...

s compared to their size than mature squid, which consume a large percentage of

fish A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...

and virtually no crustaceans. Myctophid lantern fish are seen as common prey, globally. Larger squid are known to practice cannibalism (accounting for up to 6% of diet). ''M. ingens'', as with many (if not all) large squid, has a number of predators. These include the

patagonian toothfish The Patagonian toothfish (''Dissostichus eleginoides''), also known as Chilean sea bass, mero, and icefish, is a species of notothen found in cold waters () between depths of in the southern Atlantic, Pacific, and Indian Oceans and Southern ...

king penguin The king penguin (''Aptenodytes patagonicus'') is the second largest species of penguin, smaller than but somewhat similar in appearance to the emperor penguin. King penguins mainly eat lanternfish, squid, and krill. On foraging trips, king pen ...

wandering albatross The snowy albatross (''Diomedea exulans''), also known as the wandering albatross, white-winged albatross, or goonie, is a large seabird from the family Diomedeidae Albatrosses, of the biological family (biology), family Diomedeidae, are la ...

pilot whale Pilot whales are cetaceans belonging to the genus ''Globicephala''. The two Extant taxon, extant species are the long-finned pilot whale (''G. melas'') and the short-finned pilot whale (''G. macrorhynchus''). The two are not readily distinguish ...

bottlenose whale ''Hyperoodon'' (or ''Hyperoödon'') is a genus of beaked whale, containing just two species: the Northern and Southern bottlenose whales. While not in the genus ''Hyperoodon'', Longman's beaked whales are alternatively called tropical bottle ...

dwarf sperm whale The dwarf sperm whale (''Kogia sima'') is a sperm whale that inhabits temperate and tropical oceans worldwide, in particular continental shelves and slopes. It was first described by biologist Richard Owen in 1866, based on illustrations by na ...

sperm whale The sperm whale or cachalot (''Physeter macrocephalus'') is the largest of the toothed whales and the largest toothed predator. It is the only living member of the Genus (biology), genus ''Physeter'' and one of three extant species in the s ...

, and other types of squid.CephBase: Predators of ''Moroteuthis ingens''
. Other predators include

Antarctic The Antarctic (, ; commonly ) is the polar regions of Earth, polar region of Earth that surrounds the South Pole, lying within the Antarctic Circle. It is antipodes, diametrically opposite of the Arctic region around the North Pole. The Antar ...

and

Subantarctic The sub-Antarctic zone is a physiographic region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46th parallel south, 46° and 60th parallel south, 60° south of t ...

fur seals. Image:Morotuthis ingens2.jpg, Tentacular club of ''Moroteuthopsis ingens'' Image:Moroteuthis ingens3.jpg, Piece of ventral mantle skin Image:Moroteuthis ingens4.jpg,

Gladius ''Gladius'' () is a Latin word properly referring to the type of sword that was used by Ancient Rome, ancient Roman foot soldiers starting from the 3rd century BC and until the 3rd century AD. Linguistically, within Latin, the word also came t ...

with cross-sections

References

External links

Tree of Life web project: Onykia ingensFirst observation of a double tentacle bifurcation in cephalopods
{{Taxonbar, from=Q1950090 Molluscs of the Southern Ocean Cephalopods described in 1881 Taxa named by Edgar Albert Smith