Giant squid
| Giant squid | ||||||||||||
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Giant squid ( Architeuthis dux ) |
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| Systematics | ||||||||||||
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| Architeuthidae | ||||||||||||
| Pepper , 1900 | ||||||||||||
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| Architeuthis | ||||||||||||
| Steenstrup , 1857 | ||||||||||||
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| Architeuthis dux | ||||||||||||
| Steenstrup, 1857 |
The giant squid ( Architeuthis dux ; often erroneously referred to as the giant octopus ) is widespread worldwide. Like all squids , the giant squid has ten arms grouped around the mouth, two of which are transformed into tentacles . For this reason, giant squids are assigned to the ten-armed squid or Decabrachia. The exact position within the system is unclear.
The animals are caught particularly frequently on the coasts of Norway , Great Britain , Newfoundland , Japan , Australia , New Zealand and South Africa . They probably live at a depth of over 300 meters, according to other sources, 500 to 1000 meters. For this reason, more frequent catches of the animals have only become known since the beginning of deep-sea fishing with trawls . Some remains were found in the stomachs of sperm whales .
Systematics
The giant squid, Architeuthis dux , is the only species of the genus Architeuthis , which in turn is the only genus of the family Architeuthidae within the cephalopods . Originally it was assumed that other Architeuthis species existed ( A. martensi ( Hilgendorf , 1880) , A. physeteris ( Joubin , 1900) , A. sanctipauli ( Vélain , 1877) , A. hartingii Verrill , 1875 , A. japonica pepper , 1912 , A. kirkii Robson , 1887 , A. stockii ( Kirk , 1882) ). Molecular biological studies, however, came to the conclusion that the giant squid is a single species that is found worldwide. Thus the other species were synonymous with Architeuthis dux .
description
The giant squid is dark purple to red-brown in color on the top, with the arms being lighter on the top and bottom than on the sides. Like many squids, it is able to actively change its color through chromatophores lying in the skin , by expanding or contracting them. Although the squid has luminosity (bioluminescence) , the detached luminous organs known as photophores , which carry related groups such as the Histioteuthidae , are missing .
The body of the giant squid consists, as is typical for the entire relatives, of the head almost up to a meter in length and the trunk section with a pair of fins near the end of the body. The arms are on the head. The body of the squid is narrowly conical in outline, the coat ends in a short, tail-like protrusion in adult specimens. Near the end there is a weakly muscular, flap-like fin on each side; the fins of the giant squid are relatively small compared to other squids and have an egg-shaped outline. Inside the trunk sits a transparent support structure called a gladius, a remodeling of the calcified schulp of other cephalopods. The giant squid has an ink bag . The ejected ink remains connected to a coherent structure, it does not form a cloud, as with other cuttlefish. It is believed that as a decoys it is intended to confuse and distract an attacking predator.
The animal can suck water into the mantle cavity of the trunk and expel it in a concentrated water jet through a very mobile funnel. It achieves high swimming speed and maneuverability. The cylindrical head of the squid has an eye on each side, which, with a diameter of up to 25 centimeters, is one of the largest eyes in the animal kingdom. The eyes have a dark iris and lens, but no cornea . The mouth opening in the middle of the tentacles has a chitinized, very hard beak , which is reminiscent of a parrot's beak . The beak is the only hard part that remains inside the stomach of predators like the sperm whale. Much information about the distribution of the species is only available through the analysis of such beaks in the stomach contents, which can be determined by their shape up to the species.
As is typical for all squids, the species has ten arms, eight of which are relatively short and two extremely long, which are also referred to as tentacles in the group. The normal tentacles reach a length of up to three meters with a basal circumference of 50 centimeters. The two arms of the males on the belly side are transformed into mating tools, they are called the Hectocotylus . The normal tentacles carry two rows of suction cups , which become smaller towards the tip and merge into rectangular adhesive pads distally. The main tools for catching prey are the tentacles, which when stretched out can be longer than ten meters with a basal circumference of about 25 centimeters. They are smooth close to the body, further out there are alternating suction cups and adhesive cushions in two rows. The outer (distal) end of the tentacles is widened to a weak club. This has four rows of toothed suction cups on the underside (manus or hand), of which the inner rows are significantly wider than the outer ones. The largest suction cups can reach a diameter of about 5.2 centimeters. The muscular suction cups have short stems and are stiffened on the outside by a ring made of chitin . There have been reports of scars and marks from suction cups on the skin of sperm whales , said to be eight inches in diameter; these are not scientifically documented and unbelievable.
In specialist books there are often incorrect information about size. A problem when measuring the length of giant squids is the enormous flexibility of the arms, which is why the little changeable length of the jacket is usually used as a criterion for considering the actual size. The example washed up on the beach in Lyall Bay ( Wellington ) in 1887 should be mentioned here . It had a total length of 18.3 meters, while the mantle length was only 1.8 meters, which corresponds to a total length of about 10.7 meters for a specimen with naturally long tentacles. The largest occupied coat length is 2.25 meters, with giant squids in exceptional cases reaching a standard length of 5 meters, including the head and tentacles. Most of the total length is determined by the two long thin tentacles. In fact, a giant squid could never be detected that exceeded a length of twelve meters with unstretched tentacles.
Giant squids live to be three to five years old and thus seem to be one of the longest-lived representatives of the cephalopods. However, this means that they reach their enormous size in a very short time.
In general, giant squids are the largest cephalopods. However, the much less known and more compactly built colossal squid , which, however, belongs to the Gallertkalmare family, reaches significantly larger dimensions with a coat length of up to 4 meters.
Way of life
Giant squids probably orient themselves primarily by their well-developed eyesight. Their eyes are among the largest in the entire animal kingdom. Only the eyes of the colossal squid get bigger. The huge eyes also indicate the habitat of this species - ocean depths into which only an extremely small amount of light can penetrate. Little is known about the hunting behavior of the animals. Stomach examinations mainly revealed the remains of squids (including our own species) and fish ( e.g. Hoki ). So far it has been assumed that the giant squid is more of a stalker than a persistent hunted animal. However, the first recordings of a living animal cast doubts on this thesis. The theory that sperm whales are also on his menu is bogus. It is more likely that the sperm whale is the only real predator of large fully grown giant squids , as shown by suction cup scars on the body of whales and the remains of giant squids in sperm whale stomachs. Sperm whales feed mainly on various species of squid and undertake very long and deep dives during the hunt. With diving depths of over 1000 meters (occasionally up to 3000 meters) they can prey on squids that only occur in the deep sea and cannot be reached by any other mammal. Gigantic suction cup scars on the whale skin also promoted the legend of squids that may be over 60 meters tall. But as we now know, the scars grow with the whale skin - i. H. a deep scar, which a sperm whale once received as a young animal, expands as the animal grows. In the adult it grows to a size that reflects the growth of the whale, but not the size of the squid that once caused the scar. Smaller specimens of giant squids are also eaten by various fish and sharks, and very small specimens on the surface are even eaten by deep-sea birds such as albatrosses . Medium-sized specimens also fall victim to large gray sharks or, in addition to sperm whales, other larger toothed whales that hunt for cephalopods in the deep sea.
By exchanging the sodium cation in seawater for ammonium in their muscle tissue, the giant squids, like some other squids , receive the static buoyancy they need to float in salt water . The ammonium chloride solution is noticeable by a strong odor given off by the animals. For this reason, the tough meat of the giant squid is inedible for humans.
Even less is known about the mating and development of animals than about nutrition . Apparently the male implants spermatophores under the partner's skin during mating . Several females were found with implanted spermatophores; How these ultimately fertilize the eggs is not yet known. Sperm findings show that giant squids do not seem to make a pre-selection based on sex; Spermatophores implanted by other males have also been discovered in male animals. The mating behavior shows that mating with non-fertile partners can represent an evolutionary advantage; a reproductive strategy that includes the insemination of male animals is evidently more promising than the laborious search for a female squid.
In Ozeaneum Stralsund one is crafted copy issued that of New Zealand was caught fishermen. The animal, which weighs 49 kilograms and is over six meters long (from the tip of the mantle to the tip of the tentacle), has a special feature at the rear end of the mantle: implanted spermatophores were found there, the origin of which is currently not clear.
Existence and sightings
Sometimes fantastic reports about giant octopuses were considered to be sailors' yarn until the middle of the 19th century . Although there have been reports of sightings of giant squids and encounters with these animals for centuries, the stories were mostly referred to the realm of legends and cryptozoology . Even the finds of stranded squids with lengths of well over 10 meters were not taken seriously by zoology .
- The first scientific evidence was the beak of an animal stranded in Jutland ( Denmark ) in 1854 , which came into the hands of the naturalist Japetus Steenstrup . He examined it and described the first giant squid, Architeuthis dux.
- Spanish scientists caught two giant squid on the north coast of Spain near Oviedo for the first time alive in September 2003 ; however, these died shortly afterwards. The larger one was eleven meters long and weighed 140 kilograms (according to a dpa report).
- On September 30, 2004, the Japanese researchers Tsunemi Kubodera and Kyoichi Mori took the first photos of a giant squid in its natural environment with an automatic camera and a bait off the Ogasawara Islands in the western North Pacific at a depth of 900 m. The animal lost one of its tentacles when it caught on the bait hook. The length of the tentacle was 5.5 meters, which suggests a total length of the animal of around eight meters. On this occasion it could also be observed that these animals actively hunt.
- From September 7th to October 7th, 2005 Tsunemi Kubodera, Yasuhiro Koyama and Kyoichi Mori were successful again off the Ogasawara Islands and video recordings were made at a depth of 240 to 940 meters showing a squid attacking the bait and the line several times. When attacking the bait, the squid released strong light pulses. ( Bioluminescence )
- In December 2006, Tsunemi Kubodera's team was again able to take pictures of a giant squid off the Ogasawara Islands, this time on the surface of the water and as a video recording. According to the information, the female and not yet fully grown animal was lured with a feeding bait from a depth of 600 meters and was lifted alive on board the ship, but died there - presumably from internal injuries it suffered from the change in pressure when surfacing. So far, there is no reliable information about the length of the animal; it was between three and seven meters. The catch was preserved in formalin solution for further examination at a later date.
- In July 2007, a dead giant squid with a mantle length of two meters and a total length of eight meters was washed ashore in Tasmania .
- On July 30, 2009, a six-meter specimen was recovered in the Gulf of Mexico at a depth of 1,500 meters. According to the US Department of the Interior, the crew of the research vessel Gordon Gunter caught the giant squid, which weighed around 50 kilograms.
- In July 2012, the Japanese marine biologist Tsunemi Kubodera from the National Museum of Natural Sciences in Tokyo was able to film a giant squid in its natural environment. The recordings were made in a water depth between 600 and 900 meters off the Chichi Islands . The expedition was accompanied by a film team that published a 45-minute documentary.
- In January 2013, the Discovery Channel and NHK managed to film a giant squid with the help of a team in a submarine near Chichi Island . The video clearly shows that it was slightly larger than the submarine with an approximate length of 3.5 meters. It lacked the long tentacles that were believed to have been eaten by a sperm whale. With them it would have been about nine meters long. It took the team several attempts before the recordings finally arrived. In interviews, the researchers revealed that their fear of this animal was very great, although they were prepared for it.
- On December 22, 2015, a 4-meter-long specimen was filmed up close off the coast of Toyama Bay in the Sea of Japan .
- On October 10, 2016, a live but seriously injured giant squid was photographed on the Spanish coast. The 105-kilo specimen is one of the largest giant squids ever seen alive. Due to serious injuries, which probably came from a fight with a conspecific, the specimen died shortly after the discovery and was recovered for further medical examinations.
- In June 2020, a dead giant squid over four meters long was washed up on the South African coast near Britannia Bay .
literature
- Richard Ellis: Giant Octopus of the Deep Sea. Heel Verlag, Königswinter 2002. 254 pages. ISBN 3-89365-876-9
Web links
- Tree of Life: Architeuthidae
- T. Kubodera, K. Mori: First-ever observations of a live giant squid in the wild. In: Proceedings of the Royal Society B: Biological Sciences. 272, 2005, pp. 2583-2586, doi: 10.1098 / rspb.2005.3158 - Scientific publication on the first photos of a living giant squid
- Comparison of Architeuthis and Mesonychoteuthis
Individual evidence
- ↑ Greek archos = ruler, teuthis = squid, Latin dux = prince.
- ↑ Inger Winkelmann, Paula F. Campos, Jan Strugnell, Yves Cherel, Peter J. Smith, Tsunemi Kubodera, Louise Allcock, Marie-Louise Kampmann, Hannes Schroeder, Angel Guerra, Mark Norman, Julian Finn, Debra Ingrao, Malcolm Clarke & M Thomas P. Gilbert: Mitochondrial genome diversity and population structure of the giant squid Architeuthis: genetics sheds new light on one of the most enigmatic marine species Proceedings of the Royal Society May 2013, Volume 280, No. 1759, doi: 10.1098 / rspb .2013.0273
- ↑ Bouchet, P. (2014). Architeuthis Steenstrup, 1857. World Register of Marine Species
- ^ Clyde FE Roper & Kenneth J. Boss (1982): The Giant Squid. Scientific American 246 (4): 96-105.
- ↑ P. Jereb & CFE Roper (editors): 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. FAO, Rome, 2010, ISBN 978-92-5-106720-8
- ↑ Craig R. McClain et al .: Sizing Ocean Giants: Patterns of Intraspecific Size Variation in Marine Megafauna . PeerJ 3, 2015, doi: 10.7717 / peerj.715 .
- ↑ Brad A. Seibel, Shana K. Goffredi, Erik V. Thuesen, James J. Childress, Bruce H. Robison: Ammonium content and buoyancy in midwater cephalopods (PDF; 239 kB), Journal of Experimental Marine Biology and Ecology 313 (2004 ) 375-387
- ↑ Hendrik JT Hoving, Stephanie L. Bush and Bruce H. Robison: A shot in the dark: same-sex sexual behavior in a deep-sea squid , Biology Letters (2011)
- ↑ Harald Benke (2005): The years 2003 and 2004 of the German Maritime Museum Foundation. Sea and museum. Series of publications by the Deutsches Meeresmuseum 18: 196-208.
- ↑ Tsunemi Kubodera and Kyoichi Mori in Proceedings of the Royal Society : First-ever observations of a live giant squid in the wild , December 22, 2005
- ^ FAZ : The hunter of the giant squid , December 29, 2005
- ↑ Tsunemi Kubodera, Yasuhiro Koyama, Kyoichi Mori: Observations of wild hunting behavior and bioluminescence of a large deep-sea, eight-armed squid, Taningia danae . Proc. R. Soc. B 272, 1029-1034, ( doi: 10.1098 / rspb.2006.0236 ) pdf
- ↑ Video recording 1 ( MOV ; 2.1 MB)
- ↑ Video recording 2 ( MOV ; 6.5 MB)
- ↑ Video 1 on bioluminescence (.mov; 3.7 MB)
- ↑ Video 2 on bioluminescence (.mov; 2.3 MB)
- ↑ Video 3 on bioluminescence (.mov; 2.4 MB)
- ^ Spiegel Online: Giant squid washed up on the beach
- ^ Spiegel Online : Giant squid caught in the Gulf of Mexico
- ↑ n-tv : Japanese film giant squid
- ↑ "Phantom of the Deep Sea - The Giant Squid", Terra X documentary. (No longer available online.) Archived from the original on December 3, 2016 ; accessed on July 13, 2016 .
- ↑ Giant squid gets lost in the harbor bay. In: FAZ.net. December 29, 2015, accessed December 31, 2015 .
- ↑ Creatures from the deep sea: Rare giant squid appeared near Spain . NZZ. October 11, 2016. Retrieved October 12, 2016.
- ↑ Scary find in South Africa: Large deep-sea monster washed up on the beach - marine biologists are puzzled. In: tz.de. June 19, 2020, accessed June 20, 2020 .