Berryteuthis anonychus
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Berryteuthis anonychus |
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| ( Pearcy & Voss , 1963) |
Berryteuthis anonychus is a species of squid from the Gonatidae family. It lives in the North Pacific and occurs in the subarctic waters off the North American coast. With a total length of up to one meter, of which a little more than half is accounted for by the arms, and weighing more than two kilograms, they are comparatively large squids.
features
Berryteuthis anonychus reaches a maximum coat length of about 15 centimeters. Then there are the arms and tentacles , the length of which is variable. The mantle is muscular, narrow and elongated with a clear depression on the ventral edge between the sphincter cartilages. The fins are small, oval in shape and end at the end of the coat in a gelatinous tail. They reach a length of 22 to 27% of the jacket length and a width of 49 to 55% of the jacket length. The widened ends of the tentacles are long and narrow and can reach up to 50% of their length. They have no hooks, but a large number of small, stemmed suction cups that are laid out in 12 to 15 rows and each have three to four teeth on the edge. The arms of the females have four rows of suction cups and very few, usually three to six, hooks in the area of the middle two rows of suction cups in the lower third of arms I to III. The males have no hooks; a mating arm ( hectocotylus ) is also not developed in them.
Seven rows of teeth are arranged along the radula .
distribution
Berryteuthis anonychus is distributed in the subarctic ocean areas in the North Pacific off the American and Canadian coasts, where it occurs approximately in an area between 40 ° and 60 ° north latitude and 120 ° west and 160 ° east longitude. The distribution area extends from Oregon (and partly further south) over Canada and Alaska to the Aleutian Islands . The exact distribution pattern is not known; the animals are most common in the Gulf of Alaska and in the open subarctic area south and southwest of the Gulf. They are rare south of Oregon and in southern Baja California .
Way of life
Berryteuthis anonychus is an offshore species that occurs both swimming and living on the ground on the continental shelf down to the deep sea at depths of up to 1500 meters. Especially at night, the animals can also be found in the higher water layers up to the water surface. The species is most common on the slopes of the continental shelf and seamounts , e.g. B. the Cobb – Eickelberg chain and the seamounts Warwich, Miller and Morton.
While specimens have been reported to be at depths of 1,000 to 1,500 meters, most adult animals are actually caught in the epipelagic zone up to 200 meters. They are mainly concentrated over the seamounts and the continental slopes and occur during the day at a depth of 50 to 200 meters. Investigations of statoliths have shown that the animals are more often in the pelagic area than Berryteuthis magister, for example .
Diet and predators
The squids are active both day and night and spend most of their time foraging. For this purpose, they collect in areas of oceanic eddies in which high concentrations of medium-sized and large zooplankton occur. The food mainly consists of small crustaceans such as copepods , amphipods ( Hyperiidea ), pteropods , chaetognaths and luminous shrimp or krill crabs . The food spectrum in spring is mainly characterized by copepods and chaetognaths, while diversity increases in summer and autumn. Unlike related species, they do not prey on other squids and are not cannibalistic .
They themselves are in turn of many fish species such as salmon , sea bream and tuna fish , other squid as Ommastrephes bartramii , seabirds like guillemots , short-tailed shearwaters and albatrosses and marine mammals such as the Northern Fur Seal , the fin whale , the Dall's porpoise and other toothed whales captured. Squids are a key source of food, especially for salmon in the Gulf of Alaska .
Reproduction and development
The juveniles are gregarious and widespread across the northern Pacific and southern Bering Sea. The paralarvae live planktonically and occur at times in high densities, especially in the Gulf of Alaska.
The puberty begins in males at about 70 to 80 and in the females from 70 to 90 millimeters sheath length. In contrast to other squids, there is obviously no change in the meat to a gelatinous phase. Egg-laying near the seabed takes place throughout the year, with highs in February to April and again from late June to September. The sperm packets ( spermatophores ) have a length of about 70 millimeters.
The lifespan of the animals is about a year.
Systematics
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Berryteuthis anonychus was first described scientifically in 1963 by the American zoologists William G. Pearcy and Gilbert L. Voss . They named the species as Gonatus anonychus and thus classified it in the genus Gonatus within the Gonatidae . The species was later transferred to the genus Berryteuthis due to various similarities with Berryteuthis magister , which was monotypical up to this point.
Threat and protection
The International Union for Conservation of Nature classifies Berryteuthis anonychus as not endangered ( least concern ). The classification is justified with its wide geographical distribution and the way of life in the deep sea, where it is not specifically fished. However, further research is recommended to determine the exact distribution, population dynamics, life history and ecology, and the potential threats that affect this species.
No information is available on the size and distribution of the populations .
Importance for fishing
In contrast to Berryteuthis magister , Berryteuthis anonychus is not fished in a targeted manner and therefore only occurs as bycatch . However, due to the characteristics of the meat and the size of the animals, as well as their concentrated occurrence, the species is interesting for fishing and could potentially be caught in a more targeted manner in the future.
supporting documents
- ↑ a b c d e f g h i j k C.FE Roper, EM Jorgensen, ON Katugin, P. Jereb: Family Gonatidae. In P. Jereb, CFE Roper (Ed.): Cephalopods of the world. An annotated and illustrated catalog of species known to date. Volume 2. Myopsid and Oegopsid Squids. FAO Species Catalog for Fishery Purposes No. 4, vol. 2., Rome 2010; Pp. 211-212. ( Full text )
- ↑ a b c Tsunemi Kubodera, FG Hochberg, Richard E. Young: Tree of Life web project: Berryteuthis anonychus (Engl.), 2015; accessed on March 25, 2020.
- ↑ a b c d e f g h i j k Berryteuthis anonychus in the endangered species Red List of IUCN 2020. Submitted By: I. Barratt, L. Allcock, 2014. Retrieved on April 1 2020th
Web links
- Tsunemi Kubodera, FG Hochberg, Richard E. Young: Tree of Life web project: Berryteuthis anonychus (Engl.), 2015
- Berryteuthis anonychus in the World Register of Marine Species
- Berryteuthis anonychus in the endangered Red List species the IUCN 2020 Posted by: I. Barratt, L. Allcock, 2014. Retrieved on April 1, 2020th