''Heterololigo'' is a

monotypic genus 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 ...

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 ...

s containing the single species ''Heterololigo bleekeri''. It was formerly classified in the genus ''

Loligo ''Loligo'' is a genus of squid and one of the most representative and widely distributed groups of myopsid squid. The genus was first described by Jean Baptiste Lamarck in 1798. However, the name had been used earlier than Lamarck ( Schneider, ...

''; some authors still include it there, but DNA evidence supports its separation into a genus of its own. This species is known by the common name spear squid. This squid is native to the western

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

along the coast of Asia. It can be distinguished from other species in its family by its shorter tentacles. It spawns in spring and summer in the northern part of its range, and in winter farther south. It has a life span of about one year. They are

pelagic The pelagic zone consists of the water column of the open ocean, and can be further divided into regions by depth (as illustrated on the right). The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or wa ...

, found from around 0 - 100 meters. This squid is caught for food off the coast of

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

. It lays its eggs on the underside of submerged objects. In order to increase catches, artificial substrates have been installed along the coast of Japan to provide more egg-laying sites. This species is important in biological research. Its

mitochondrial genome Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...

has been sequenced. Its

neuron A neuron, neurone, or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. The neuron is the main component of nervous tissue in all animals except sponges and placozoa. N ...

s are used in neurobiology research. Like most Cephalopods, they are

gonochoric In biology, gonochorism is a sexual system where there are only two sexes and each individual organism is either male or female. The term gonochorism is usually applied in animal species, the vast majority of which are gonochoric. Gonochorism c ...

. Male adults will usually die after spawning, and female adults after brooding. A unique aspect of the reproduction of this species has been well studied. The female has two sperm-storage sites in its body. There are two types of males, the larger "consort" males and the smaller "sneaker" males. Consorts insert sperm into the oviduct of the female, and sneakers place sperm into specialized tissue near the female's mouth.Iwata, Y., et al. (2014)
Dimorphic sperm-transfer strategies and alternative mating tactics in loliginid squid.
''J Mollus Stud'' online abstract. The two male types produce different types of sperm, as well: the large consorts produce sperm with short flagella, while the sneaker males have sperm with longer flagella. The consort sperm fertilize eggs internally, while sneaker sperm fertilize the eggs as they emerge from the female's body and brush past the external sperm-deposition site near the mouth.Hirohashi, N., et al. (2014). Respiratory CO₂ mediates sperm chemotaxis in squids. ''In'': ''Sexual Reproduction in Animals and Plants'' (pp. 13-21). Springer Japan.

References

{{Taxonbar, from=Q872262 Squid Monotypic mollusc genera Cephalopod genera Molluscs described in 1866