The Antarctic giant squid [1] , or the Antarctic deep-sea squid [2] ( lat. Mesonychoteuthis hamiltoni ) is a deep-sea species of squid and the only representative of the genus Mesonychoteuthis . In the unscientific press and popular literature, it is usually called a " colossal squid ", using a direct translation from one of the English names.
| Antarctic Giant Squid | ||||||||||||||||||
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 Mesonychoteuthis hamiltoni | ||||||||||||||||||
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| Mesonychoteuthis hamiltoni Robson , 1925 | ||||||||||||||||||
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It was first described in 1925 by the British zoologist G.K. Robson (Guy Coburn Robson; 1888-1945) on two tentacles from the stomach of a sperm whale , caught south of the South Shetland Islands [3] . Since the description of the species about him there was no more information for the next more than 40 years. In fact, the first information after a long break appeared only in 1970, when 4 larvae of M. hamiltoni from the Atlantic sector of the Antarctic were described [4] , and the first capture of an adult individual of this species, a female with a mantle length of 117 cm, with a different depth trawl only in 1979 [5] .
Endemic of the Antarctic. It is one of the most massive and largest species of squid in Antarctic waters [2] . According to estimates, its maximum size is not less than 10 m, and possibly even 13-14 m of total length, second only to the giant squid of the genus Architeuthis from the Northern Hemisphere, and noticeably exceeds its mass (about half a ton); in Antarctica, the largest squid after it is Kondakovia longimana (total length up to 2.2 m).
An interesting feature of all giant, as well as all Antarctic and deep-sea squids is the presence of ammonium chloride in their body, which reduces the specific gravity of the body and gives the squids neutral buoyancy. Unlike small squids with negative buoyancy, which are forced to constantly use the very energy-consuming mechanism of a jet stream released from a funnel, Antarctic squids can soar virtually without movement in the water column.
Content
Description
A very large species with an elongated body, mantle length up to 3 m, a total length of about 9-10 m and a maximum known weight of 495 kg. The mantle is wide, tapering in the last third of its length into a narrow long pointed tail. The thickness of the walls of the mantle is about 5-6 cm; The mantle fabric is soft. The occipital and funnel cartilages are short, thick, somewhat curved, without tuberculosis in adult or almost adult squids. The fins are large, thick, muscular, terminal, make up almost half the length of the mantle and, when extended, form a profile (when viewed from above and below) in the form of a heart. The eyes are very large, with two photophores ; eye diameter reaches 27 cm. Tentacles with two rows of suction cups on clubs, two longitudinal rows of well-developed hooks (up to 26), located medially, and small side suckers. The trapping arms are very thick, long and muscular, with wide protective membranes at the base and thinning towards the ends; in the middle part of the hands there are from three to 11 pairs of hood-shaped hooks, in the last third of the length there are suction cups. Chitin beak is thick, hard and powerful [1] [6] .
Distribution and bathymetric distribution
Distributed in the Southern Ocean circumpolarly. In Antarctic waters, it forms clusters, and outside the Antarctic convergence it keeps sparsely. The most northern finds are known south of the shores of New Zealand, South Africa and South America. It lives mainly in the deep Antarctic waters, where it occurs at depths of up to 2-4 thousand meters. As an indicator of the hypothetical presence of this squid in any area of the Southern Ocean, water surface temperature in the range from −1.9 to +2 ° C can be considered. The maximum occurrence of this species occurs even in a narrower temperature range - from −0.9 to 0 ° C. Adult squids are usually found at a depth of 200-700 m (mesopelagial) to 700-2000 m (bathipelagial). In December – March, it is especially common in the high latitudes of the Antarctic between 60 and 70 degrees south latitude [1] [2] [6] .
Dimensions
Females are larger than males. In the stomachs of sperm whales, individuals of both sexes of squid with a mantle size from 80 to 250 cm and weighing up to 250 kg are noted. In the largest individuals, the length of the mantle, obviously, can reach 4 meters. In 2007, in the Ross Sea, New Zealand fishermen on the longline vessel “San Aspirin”, engaged in fishing for Antarctic toothfish , caught the largest ever caught Antarctic giant squid with a total length of about 10 meters, with a mantle length of 3 m and a weight of 495 kg [7] [8] [9] .
Lifestyle
Very little is known about the peculiarities of biology and the life cycle of this squid, since cases of their capture are extremely rare. It is the main object of hunting sperm whales (up to 60% in food) [10] and Antarctic toothfish , it is also eaten by killer whales , grinds and southern elephant seals , and albatrosses feed on immature small individuals [6] . The main source of primary information on the lifestyle of this squid was data on the nutrition of sperm whales obtained by the Soviet researcher V. L. Yukhov during the open whaling period from 1967 to 1974 [2]
A passive predator and a typical ichthyophage , hovering in the water column in anticipation of passing prey. The main food item of the Antarctic giant squid is the luminous anchovies of the Myctophidae family (Myctophidae), as well as other mesopelagic fish , mainly the Paralepididae family. In addition, other squids are found in the diet; and at immature age in the early stages of development feeds mainly on zooplankton .
It begins to mature for the first time with a mantle length of about 1 m and a weight of about 25-30 kg. The length of spermatophores is about 170-250 mm, and potential fertility is about 4-4.2 million oocytes . In November – April, the gonads of females are at the II – III stage of maturity. The difference in oocyte diameters indicates their asynchronous growth and development. Spawning probably occurs in late winter - early spring.
Potential Use in Nutrition
In this squid, unlike most other types of Antarctic squid, ammonium chloride solution, which gives the animal neutral buoyancy and a characteristic ammonia odor, is not in the mantle tissue, but in a special coelomic bag. This bag is easily removed together with the entrails, therefore, squid mantle meat (yield by weight up to 67%) is edible and, moreover, has a gentle pleasant taste [2] [11] . According to modern estimates, the biomass of this squid can be about 90 million tons [6] .
Notes
- ↑ 1 2 3 FAO species identification sheets for fishery purposes, Southern Ocean: fishing areas 48, 58, and 88, CCAMLR Convention area. Fischer W. and Hureau J.-C. (Eds). Vol. 1. (1985): Rome, FAO. 1-232 p.
- ↑ 1 2 3 4 5 Yuhov V. L. (2013): Some features of the biology of Antarctic deep-sea squid (ACG) - Mesonychoteuthis hamiltoni Robson, 1925. In the book: Internationalization of Antarctic research - way to spiritual unity of humanity. VI IAC 2013. VI International Antarctic Conference. Kyiv, Ukraine, May 15-17, 2013. P.165-157
- ↑ Robson GC (1925): On Mesonychoteuthis, a new genus of oegopsid, Cephalopoda. - Annals and Magazine of Natural History, Series 9, 16: 272-277.
- ↑ Filippova Yu.A., Yukhov V.L. (1979): Species composition and distribution of cephalopods in the meso- and bathipelagic Antarctic waters. In: Antarctica, Commission reports. Vol. 18. M .: Science. S. 175-187.
- ↑ Rodhouse PG, Clark MR (1985): Growth and distribution of young Mesonychoteuthis hamiltoni Robson (Mollusca: Cephlopoda) an Antarctic squid. Vie Milieu, 35 (3/4). P. 223-230.
- ↑ 1 2 3 4 Jereb P., Roper CFE (eds). (2010): Cephalopods of the world. An annotated and illustrated catalog of cephalopod species known to date. Volume 2. Myopsid and Oegopsid Squids. FAO Species Catalog for Fishery Purposes. No. 4, Vol. 2. Rome, FAO. 605p. 10 color plates.
- ↑ A colossal squid of record sizes captured in New Zealand . membrana.ru (February 22, 2007). Date of treatment May 13, 2010. Archived March 23, 2012.
- ↑ A colossal squid gets into the microwave . membrana.ru (March 22, 2007). Date of treatment May 13, 2010. Archived March 23, 2012.
- ↑ Captain John Bennett examines an adult colossal squid accidentally caught by fishers in 2007.
- ↑ Filippova Yu.A., Yukhov V.L. (1983): Squids of the Antarctic region. In: Systematics and Ecology of Cephalopods. L .: Zoological Institute of the USSR Academy of Sciences. S. 72-75.
- ↑ Filippova Yu.A., Stygar I.E. (1986): Species composition, biology, distribution and fishing of squid Antarctic and temperate waters of the Southern Ocean. Overview information. Series: Fisheries Management of the Oceans. Vol. 1. M.: TSNIITEIRH. S. 1-40.
Literature
- Clarke, MR 1980 . Cephalopoda in the diet of sperm whales of the southern hemisphere and their bearing on sperm whale biology. - Discovery Reports 37: 1-324.