Colossal squid | |
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Depiction with an inflated mantle | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Cephalopoda |
Order: | Oegopsida |
Superfamily: | Cranchioidea |
Family: | Cranchiidae |
Subfamily: | Taoniinae |
Genus: | Mesonychoteuthis Robson, 1925 |
Species: | M. hamiltoni |
Binomial name | |
Mesonychoteuthis hamiltoni | |
Global range of M. hamiltoni |
The colossal squid (Mesonychoteuthis hamiltoni) is the largest member of its family Cranchiidae, the cockatoo or glass squids, with its second largest member being Megalocranchia fisheri . It is sometimes called the Antarctic cranch squid or giant squid (not to be confused with the giant squid in genus Architeuthis) and is believed to be the largest squid species in terms of mass. [3] It is the only recognized member of the genus Mesonychoteuthis and is known from only a small number of specimens. [4] The species is confirmed to reach a mass of at least 495 kilograms (1,091 lb), though the largest specimens—known only from beaks found in sperm whale stomachs—may perhaps weigh as much as 600–700 kilograms (1,300–1,500 lb), [5] [6] making it the largest known invertebrate. [3] Maximum total length has been estimated between 10 metres (33 ft) and 14 metres (46 ft) but the former estimate is more likely. [7] [8] The colossal squid has the largest eyes of any known creature ever to exist, with an estimated diameter of 27–30 cm (11–12 in) [9] to 40 cm (16 in) for the largest collected specimen.
The species has similar anatomy to other members of its family, although it is the only member of Cranchiidae to display hooks on its arms, suckers and tentacles. [10] [11] It is known to inhabit the circumantarctic Southern Ocean. [3] It is presumed to be an ambush predator, and is likely a key prey item of the sperm whale. [12] [13]
The first specimens were discovered and described in 1925. [14] In 1981, an adult specimen was discovered; in 2003, a second specimen was collected. [15] [16] Captured in 2007, the largest colossal squid weighed 495 kilograms (1,091 lb), [17] and is now on display at the Museum of New Zealand Te Papa Tongarewa. [18] [19]
In 2022-23 there were several attempts made by scientists including an ocean exploration non-profit KOLOSSAL to find and film the colossal squid in its natural habitat for the first time to learn more about its biology and ecological behavior. [20] [21] The science team used a tourism vessel [22] [23] to survey 36 locations throughout the Southern Ocean and may have filmed for the first time a small juvenile colossal squid. Researchers have confirmed it is a species of glass squid, but due to marine snow the footage has been harder to confirm without a DNA analysis, and may be Galiteuthis glacialis or a new species of glass squid unknown to science. [24] [25] [26] [27] If confirmed, this would be the first filming of a colossal squid underwater in its natural habitat and the first footage of a juvenile.
More expeditions are being planned for and before 2025, the hundredth year anniversary of the first discovery of the colossal squid, in attempts to find and film an adult colossal squid living freely in its natural environment. [28]
The colossal squid shares features common to all squids: a mantle for locomotion, one pair of gills, a beak or tooth, and certain external characteristics like eight arms and two tentacles, a head, and two fins. [10] In general, the morphology and anatomy of the colossal squid are the same as any other squid. [10] However, there are certain morphological characteristics that separate the colossal squid from other squids in its family: the colossal squid is the only squid in its family whose arms and tentacles are equipped with hooks, either swivelling or three-pointed. [11] There are squids in other families that also have hooks, but no other squid in the family Cranchiidae. [10]
Unlike most squid species, the colossal squid exhibits abyssal gigantism, as it is the heaviest living invertebrate species, reaching weights up to 495 kg (1,091 lb). [3] For comparison, squids typically have a mantle length of about 30 cm (12 in) and weigh about 100–200 g (3+1⁄2–7 oz). [10]
The giant squid also exhibits abyssal gigantism, but the colossal squid is heavier. [29] Although it is unclear what the maximum weight for colossal squids is, analysis of squid beak dimensions from sperm whale stomachs provided estimates that colossal squids may weigh up to 700 kg or 1,500 lb. [5] [6]
The colossal squid also has the largest eyes documented in the animal kingdom, with a diameter of 27–30 cm (11–12 in). [30] [31]
The squid's known range extends thousands of kilometres north of Antarctica to southern South America, southern South Africa, and the southern tip of New Zealand, making it primarily an inhabitant of the entire circumantarctic Southern Ocean. [3] Colossal squid are also sighted often near Cooperation Sea and less near Ross Sea because of its prey and competitor, the Antarctic toothfish. [32] The region between the Weddell Sea and the western Kerguelen archipelago has been deemed a "hotspot" based on characteristics of the habitat. [33] The squid's vertical distribution appears to correlate directly with age. Young squid are found between 0–500 m (0–1,640 ft), adolescent squid are found 500–2,000 m (1,600–6,600 ft) and adult squid are found primarily within the mesopelagic and bathypelagic regions of the open ocean. [3]
Little is known about their behaviour, but it is believed to feed on prey such as chaetognatha, large fish such as the Patagonian toothfish, and smaller squid in the deep ocean. [34] A recent study by Remeslo, Yakushev and Laptikhovsky revealed that Antarctic toothfish make up a significant part of the colossal squid's diet; of the 8,000 toothfish brought aboard trawlers between 2011 and 2014, seventy-one showed clear signs of attack by colossal squid. [35] A study in Prydz Bay region of Antarctica found squid remains in a female colossal squid's stomach, suggesting the possibility of cannibalism within this species. [36] Studies measuring the δ15N content of the chitinous beaks of cephalopods to determine trophic ecology levels have demonstrated that the colossal squid is a top predator that is positively correlated with its increased size. [37] This new confirmation of the colossal squid's trophic level suggests that it likely preys on large fishes and smaller squids, according to its size, and that its predators include sperm whales and sleeper sharks. [37]
The colossal squid is thought to have a very slow metabolic rate, needing only around 30 grams (1 oz) of prey daily for an adult with a mass of 500 kilograms (1,100 lb). [38] Estimates of its energy requirements suggest it is a slow-moving ambush predator, using its large eyes primarily for prey-detection rather than engaging in active hunting. [38] [13]
Many sperm whales have scars on their backs, believed to be caused by the hooks of colossal squid. Colossal squid are a major prey item for sperm whales in the Antarctic; 14% of the squid beaks found in the stomachs of these sperm whales are those of the colossal squid, which indicates that colossal squid make up 77% of the biomass consumed by these whales. [39] Many other animals also feed on colossal squid, including the beaked whales, such as southern bottlenose whales, Cuvier's and Baird's beaked whales; the beaked whales essentially resemble oversized dolphins, some with a more pronounced underbite on their snout (or "beak"). They are among the deepest-diving cetaceans ever recorded, besides the sperm whale. This places the beaked whales as some of the few food competitors of the sperm whale. Other possible squid predators include the pilot whale, killer whales, larger southern elephant seals, Patagonian toothfish, [40] southern sleeper sharks (Somniosus antarcticus), Antarctic toothfish, and albatrosses (e.g., the wandering and sooty albatrosses). [3] However, beaks from mature adults have only been recovered from large predators (i.e. sperm whales and southern sleeper sharks), while the other predators only eat juveniles or young adults. [41]
Not much is known about the colossal squid's reproductive cycle, although it does have two distinct sexes. Many species of squid, however, develop sex-specific organs as they age and develop. [42] The adult female colossal squid has been discovered in much shallower waters, which likely implies that females spawn in shallower waters, rather than their normal depth. [3] Additionally, the colossal squid has a high possible fecundity reaching over 4.2 million oocytes which is quite unique compared to other squids in such cold waters. [42] Colossal squid oocytes have been observed at sizes ranging from as large as 3.2x2.1 mm to as small as 1.4x0.5 mm. Sampling of colossal squid ovaries show an average of 2175 eggs per gram. [34] Young squid are thought to spawn near the summer time at surface temperatures of −0.9–0 °C (30.4–32.0 °F). [32]
For pelagic organisms of similar weight to the colossal squid, such as the swordfish, the average eye diameter required for visual detection is 10 cm, but the colossal squid's are as large as 30 cm (12 in). [43] [44] The allowed increase in visual detection strategies, including reduced diffraction blurring and greater contrast distinction, must be extremely beneficial to the colossal squid to justify the large energetic expenses to grow, move, camouflage, and maintain these eyes. [43] The colossal squid's increased pupil size has been mathematically proven to overcome the visual complications of the pelagic zone (the combination of downwelling daylight, bioluminescence, and light scattering with increasing distance), especially by monitoring larger volumes of water at once and by detecting long-range changes in plankton bioluminescence via the physical disruption of large moving objects (e.g., sperm whales). [43]
The colossal squid's eyes glow in the dark via long, rectangular light-producing photophores located next to the lens on the front of both eyeballs. [45] Symbiotic bacteria reside within these photophores and luminesce through chemical reaction. [46]
It is hypothesized that the colossal squid's eyes can detect predator movement beyond 120 m, which is the upper limit of the sperm whale's sonar range. [43]
Squid have been found to detect the movement of sound waves via organs called statocysts (similar to the human cochlea). [47] Squid statocysts likely respond to low frequency sounds less than 500 Hz, similar to pelagic fish. [47] Colossal squid are essentially deaf to high frequencies, such as whale sonar, so they rely largely on visual detection mechanisms to avoid predation. [43] [48]
The colossal squid, species Mesonychoteuthis hamiltoni, was discovered in 1925. [14] This species belongs to the class Cephalopoda and family Cranchiidae. [49]
Most of the time, full colossal squid specimens are not collected; as of 2015, only 12 complete colossal squids had ever been recorded, with only half of these being full adults. [4] Commonly, beak remnants of the colossal squid are collected; 55 beaks of colossal squids have been recorded in total. [4] Less commonly (four times), a fin, mantle, arm or tentacle of a colossal squid was collected. [4]
The species was first discovered in the form of two arm crowns found in the stomach of a sperm whale in the winter of 1924–1925. [14] This species, then named Mesonychoteuthis hamiltoni after E. Hamilton who made the initial discovery, was formally described by Guy Coburn Robson in 1925. [14]
In 1981, a Soviet Russian trawler in the Ross Sea, off the coast of Antarctica, caught a large squid with a total length of over 4 m (13 ft), which was later identified as an immature female of M. hamiltoni. [15] In 2003, a complete specimen of a subadult female was found near the surface with a total length of 6 m (20 ft) and a mantle length of 2.5 m (8 feet 3 inches). [16] In 2005, the first full living specimen was captured at a depth of 1,625 m (5,331 ft) while taking a toothfish from a longline off South Georgia Island. [50] Although the mantle was not brought aboard, its length was estimated at over 2.5 m (8 feet 3 inches), and the tentacles measured 2.3 metres (7 feet 7 inches). [50] The animal is thought to have weighed between 150 and 200 kg (330 and 440 lb). [50]
The largest recorded specimen was a female, which are thought to be larger than males, captured in February 2007 by a New Zealand fishing boat in the Ross Sea off Antarctica. [31] The squid was close to death when it was captured and subsequently was taken back to New Zealand for scientific study. [51] The specimen was initially estimated to measure about 10 metres in total length and weigh about 450 kg.
Thawing and dissection of the specimen took place at the Museum of New Zealand Te Papa Tongarewa. [52] AUT biologist Steve O'Shea, Tsunemi Kubodera, and AUT biologist Kat Bolstad were invited to the museum to aid in the process, joined by Marine Ecologist Mark Fenwick and Dutch scientist Olaf Blaauw. [52] Media reports suggested scientists at the museum were considering using a giant microwave to defrost the squid because thawing it at room temperature would take several days and it would likely begin to decompose on the outside while the core remained frozen. [53] However, they later opted for the more conventional approach of thawing the specimen in a bath of salt water. [54] After thawing, it was found that the specimen was 495 kg with a mantle length of 2.5 m and a total length of only 4.2 m, probably because the tentacles shrank once the squid was dead. [17]
Parts of the specimen have been examined:
The Museum of New Zealand Te Papa Tongarewa began displaying this specimen from 13 December 2008. The exhibition was closed between 2018 and 2019, but is currently open again for public viewing at Te Papa. [18]
The colossal squid has been assessed as "least concern" on the IUCN Red List. [1] Furthermore, colossal squid are not targeted by fishermen; rather, they are only caught when they attempt to feed on fish caught on hooks. [58] Additionally, due to their habitat, interactions between humans and colossal squid are considered rare. [59]
A squid is a mollusc with an elongated soft body, large eyes, eight arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida. Like all other cephalopods, squid have a distinct head, bilateral symmetry, and a mantle. They are mainly soft-bodied, like octopuses, but have a small internal skeleton in the form of a rod-like gladius or pen, made of chitin.
The giant squid is a species of deep-ocean dwelling squid in the family Architeuthidae. It can grow to a tremendous size, offering an example of abyssal gigantism: recent estimates put the maximum size at around 12–13 m (39–43 ft) for females and 10 m (33 ft) for males, from the posterior fins to the tip of the two long tentacles. The mantle of the giant squid is about 2 m long, and the length of the squid excluding its tentacles rarely exceeds 5 m (16 ft). Claims of specimens measuring 20 m (66 ft) or more have not been scientifically documented.
Cuvier's beaked whale, goose-beaked whale, or ziphius is the most widely distributed of all beaked whales in the family Ziphiidae. It is smaller in size than most baleen whales—and indeed the larger toothed cetaceans —yet it is large among the beaked whales and smaller cetaceans, appearing somewhat like a bigger and stockier bottlenose dolphin. Cuvier's beaked whale is pelagic, generally inhabiting waters deeper than 300 m (1,000 ft), though it has been observed closer to shore on occasion. In these offshore waters, Cuvier's beaked whale executes some of the deepest, longest recorded dives among whales, and extant mammals, at 2,992 m (9,816 ft), for 222 minutes. While likely diving to forage and hunt prey, such as cephalopods, and potentially evade predators, the frequency and exact reason for these extraordinary dives is unclear. Despite its deepwater habitat, it is one of the most frequently-spotted beaked whales when surfacing.
The Antarctic toothfish, also known as the Antarctic cod, is a large, black or brown fish found in very cold (subzero) waters of the Southern Ocean near Antarctica. It is the largest fish in the Southern Ocean, feeding on shrimp and smaller fish, and preyed on by whales, orcas, and seals. It is caught for food and marketed as Chilean sea bass together with its sister species, the more northerly Patagonian toothfish. Often mistakenly called "Antarctic cod", the Antarctic toothfish belongs to the notothen family (Nototheniidae), a family of fish genera that are abundant near Antarctica.
The vampire squid is a small cephalopod found throughout temperate and tropical oceans in extreme deep sea conditions. The vampire squid uses its bioluminescent organs and its unique oxygen metabolism to thrive in the parts of the ocean with the lowest concentrations of oxygen. It has two long retractile filaments, located between the first two pairs of arms on its dorsal side, which distinguish it from both octopuses and squids, and places it in its own order, Vampyromorphida, although its closest relatives are octopods. As a phylogenetic relict, it is the only known surviving member of its order.
The family Cranchiidae comprises the approximately 60 species of glass squid, also known as cockatoo squid, cranchiid, cranch squid, or bathyscaphoid squid. Cranchiid squid occur in surface and midwater depths of open oceans around the world. They range in mantle length from 10 cm (3.9 in) to over 3 m (9.8 ft), in the case of the colossal squid. The common name, glass squid, derives from the transparent nature of most species. Cranchiid squid spend much of their lives in partially sunlit shallow waters, where their transparency provides camouflage. They are characterised by a swollen body and short arms, which bear two rows of suckers or hooks. The third arm pair is often enlarged. Many species are bioluminescent organisms and possess light organs on the undersides of their eyes, used to cancel their shadows. Eye morphology varies widely, ranging from large and circular to telescopic and stalked. A large, fluid-filled chamber containing ammonia solution is used to aid buoyancy. This buoyancy system is unique to the family and is the source of their common name "bathyscaphoid squid", after their resemblance to a bathyscaphe. Often the only organ that is visible through the transparent tissues is a cigar-shaped digestive gland, which is the cephalopod equivalent of a mammalian liver. This is usually held in a vertical position to reduce its silhouette and a light organ is sometimes present on the lower tip to further minimise its appearance in the water.
Taoniinae is a subfamily containing ten genera of glass squids.
Taningia danae, the Dana octopus squid, is a species of squid in the family Octopoteuthidae. It is one of the largest known squid species, reaching a mantle length of 1.7 m (5.6 ft) and total length of 2.3 m (7.5 ft). The largest known specimen, a mature female, weighed 161.4 kg (356 lb).[nb a]
Cephalopods, which include squids and octopuses, vary enormously in size. The smallest are only about 1 centimetre (0.39 in) long and weigh less than 1 gram (0.035 oz) at maturity, while the giant squid can exceed 10 metres (33 ft) in length and the colossal squid weighs close to half a tonne (1,100 lb), making them the largest living invertebrates. Living species range in mass more than three-billion-fold, or across nine orders of magnitude, from the lightest hatchlings to the heaviest adults. Certain cephalopod species are also noted for having individual body parts of exceptional size.
Moroteuthopsis longimana, also known as the giant warty squid or longarm octopus squid, is a large species of hooked squid. It attains a mantle length of at least 85 cm and probably over 1.15 m. The largest complete specimen of this species, measuring 2.3 m in total length, was found in Antarctica in 2000.
The southern sleeper shark, or Whitley's sleeper shark, is a deepwater benthopelagic sleeper shark of the family Somniosidae found in the southern and subantarctic extremes of the Atlantic, Indian and Pacific Oceans, and some northern reaches of the Antarctic oceans. It has been recorded near the southernmost areas of South America, near South Africa, southern Australia, Tasmania and New Zealand, as well as more remote locations in the south-central Indian Ocean.
Steve O'Shea is a marine biologist and environmentalist known for his research on giant squid.
The seven-arm octopus, also known as the blob octopus or sometimes called septopus, is one of the two largest known species of octopus; the largest specimen ever discovered had an estimated total length of 3.5 m (11 ft) and mass of 75 kg (165 lb). The only other similarly large extant species is the giant Pacific octopus, Enteroctopus dofleini.
Cephalopod attacks on humans have been reported since ancient times. A significant portion of these attacks are questionable or unverifiable tabloid stories. Cephalopods are members of the class Cephalopoda, which includes all squid, octopuses, cuttlefish, and nautiluses. Some members of the group are capable of causing injury or death to humans.
Stauroteuthis gilchristi is a species of small pelagic octopus found at great depths in the south Atlantic Ocean. It is believed to be one of a very small number of octopuses to exhibit bioluminescence, like its sister taxon Stauroteuthis syrtensis.
All extant cephalopods have a two-part beak, or rostrum, situated in the buccal mass and surrounded by the muscular head appendages. The dorsal (upper) mandible fits into the ventral (lower) mandible and together they function in a scissor-like fashion. The beak may also be referred to as the mandibles or jaws. These beaks are different from bird beaks because they crush bone while most bird beaks do not.
Teuthowenia megalops, sometimes known as the Atlantic cranch squid, is a species of glass squid from the subarctic and temperate waters of the northern Atlantic Ocean. They are moderately sized squid with a maximum mantle length of 40 cm (16 in). Their very large eyes are the source for the specific name megalops. Like other members of the genus Teuthowenia, they are easily recognizable by the presence of three bioluminescent organs (photophores) on their eyeballs.
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