Colossal squid
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 mistaken for the giant squid known as 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 at 9–10 metres (30–33 ft).[7] The colossal squid has the largest eyes of any known creature ever to exist, with an estimated diameter of 27 cm (11 in).[8]
Colossal squid | |
---|---|
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 species has similar anatomy to other members of its family, although it is the only member of Cranchiidae to display hooks on its arms and tentacles.[9][10] It is known to inhabit the circumantarctic Southern Ocean.[3] Although little is known about the behaviour, it is known to use bioluminescence to attract prey.[11] It is presumed to be an ambush predator, and is a major prey of the sperm whale.[12][13]
The first specimens were discovered and described in 1925.[14] In 1981, an adult specimen was discovered, and 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]
Morphology
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.[9] In general, the morphology and anatomy of the colossal squid are the same as any other squid.[9] 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 with hooks, either swivelling or three-pointed, equipped on its arms and tentacles.[10] There are squids in other families that also have hooks, but no other squid in the family Cranchiidae.[9]
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).[9]
The giant squid also exhibits abyssal gigantism, but the colossal squid is heavier and slightly shorter (having an estimated maximum size of 9-10 m, compared to 13 m for the giant squid).[20] 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 an estimated diameter of 30–40 cm (12–16 in).[21][22]
Distribution and habitat
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 predator and competitor, the Antarctic toothfish.[23] The region between the Weddell Sea and the western Kerguelen archipelago has been deemed a “hotspot” based on characteristics of the habitat.[24] 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]
Behavior
Feeding
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 using bioluminescence.[11] 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.[25] 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.[26] 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.[27] 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.[27]
Metabolism
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).[28] 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.[28][13]
Predation
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.[29] 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,[30] 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.[31]
Reproduction
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.[32] The adult female colossal squid has been discovered in much shallower waters, which likely implies that females spawn in shallower waters 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.[32] 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.[11] Young squid are thought to spawn near the summer time at surface temperatures of −0.9–0 °C (30.4–32.0 °F).[23]
Vision
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 27 cm.[33][34] 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.[33] 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).[33]
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.[35] Symbiotic bacteria reside within these photophores and luminesce through chemical reaction.[36]
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.[33]
Hearing
Squid have been found to detect the movement of sound waves via organs called statocysts (similar to the human cochlea).[37] Squid statocysts likely respond to low frequency sounds less than 500 Hz, similar to pelagic fish.[37] Colossal squid are essentially deaf to high frequencies, such as whale sonar, so they rely largely on visual detection mechanisms to avoid predation.[33][38]
Taxonomy and history
The colossal squid, species Mesonychoteuthis hamiltoni, was discovered in 1925.[14] This species belongs to the class Cephalopoda and family Cranchiidae.[39]
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]
First specimens
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]
Entire specimens
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.[40] 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).[40] The animal is thought to have weighed between 150 and 200 kg (330 and 440 lb).[40]
Largest known specimen
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.[22] The squid was close to death when it was captured and subsequently was taken back to New Zealand for scientific study.[41] The specimen was initially estimated to measure about 10 metres in total length and weigh about 450 kg.
Defrosting and dissection, April–May 2008
Thawing and dissection of the specimen took place at the Museum of New Zealand Te Papa Tongarewa.[42] 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.[42] 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.[43] However, they later opted for the more conventional approach of thawing the specimen in a bath of salt water.[44] 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 beak is considerably smaller than some found in the stomachs of sperm whales,[45][46] suggesting other colossal squid are much larger than this one.[45][46]
- The eye is 27 cm (10+1⁄2 in) wide, with a lens 12 cm (4+1⁄2 in) across. This is the largest eye of any known animal.[21] These measurements are of the partly collapsed specimen; alive, the eye was probably 30[22] to 40 cm (12 to 16 in) across.[47]
- Inspection of the specimen with an endoscope revealed ovaries containing thousands of eggs.[22]
Exhibition
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]
Conservation status
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.[49] Additionally, due to their habitat, interactions between humans and colossal squid are considered rare.[50]
See also
References
- Barratt, I.; Allcock, L. (2014). "Mesonychoteuthis hamiltoni". IUCN Red List of Threatened Species. 2014: e.T163170A980001. doi:10.2305/IUCN.UK.2014-1.RLTS.T163170A980001.en. Retrieved 15 September 2022.
- Bieler R, Bouchet P, Gofas S, Marshall B, Rosenberg G, La Perna R, Neubauer TA, Sartori AF, Schneider S, Vos C, ter Poorten JJ, Taylor J, Dijkstra H, Finn J, Bank R, Neubert E, Moretzsohn F, Faber M, Houart R, Picton B, Garcia-Alvarez O (eds.). "Mesonychoteuthis hamiltoni G. C. Robson, 1925". MolluscaBase. World Register of Marine Species. Retrieved 15 September 2022.
- Rosa, Rui; Lopes, Vanessa M.; Guerreiro, Miguel; Bolstad, Kathrin & Xavier, José C. (30 March 2017). "Biology and ecology of the world's largest invertebrate, the colossal squid (Mesonychoteuthis hamiltoni): a short review" (PDF). Polar Biology. 40 (9): 1871–1883. doi:10.1007/s00300-017-2104-5. S2CID 15480545.
- McClain, Craig R.; Balk, Meghan A.; Benfield, Mark C.; Branch, Trevor A.; Chen, Catherine; Cosgrove, James; Dove, Alistair D.M.; Gaskins, Lindsay C.; Helm, Rebecca R.; Hochberg, Frederick G.; Lee, Frank B.; Marshall, Andrea; McMurray, Steven E.; Schanche, Caroline; Stone, Shane N. & Thaler, Andrew D. (2015). "Sizing ocean giants: patterns of intraspecific size variation in marine megafauna". PeerJ. 3: e715. doi:10.7717/peerj.715. PMC 4304853. PMID 25649000.
- [Te Papa] (2019). How big is the colossal squid on display? Museum of New Zealand Te Papa Tongarewa.
- [Te Papa] (2019). The beak of the colossal squid. Museum of New Zealand Te Papa Tongarewa.
- Roper, C.F.E. & P. Jereb (2010). Family Cranchiidae. In: P. Jereb & C.F.E. Roper (eds.) Cephalopods of the world. An annotated and illustrated catalogue of species known to date. Volume 2. Myopsid and Oegopsid Squids. FAO Species Catalogue for Fishery Purposes No. 4, Vol. 2. FAO, Rome. pp. 148–178.
- "The eyes of the colossal squid". Museum of New Zealand Te Papa Tongarewa, Wellington, NZ. 29 December 2016. Retrieved 15 September 2022.
- Jereb, P. & Roper, C.F.E. (2010). Cephalopods of the World. Food and Agriculture Organization of the U.N. Vol. 2. United Nations. pp. 6–10.
- "Hooks and suckers". Te Papa (blog). 30 April 2008. Retrieved 30 September 2011 – via Blog.tepapa.govt.nz.
- Remeslo, Alexander; Yukhov, Valentin; Bolstad, Kathrin & Laptikhovsky, Vladimir (May 2019). "Distribution and biology of the colossal squid, Mesonychoteuthis hamiltoni: New data from depredation in toothfish fisheries and sperm whale stomach contents". Deep Sea Research Part I: Oceanographic Research Papers. 147: 121–127. Bibcode:2019DSRI..147..121R. doi:10.1016/j.dsr.2019.04.008. S2CID 146043830.
- Nilsson, Dan-Eric; Warrant, Eric J.; Johnsen, Sönke; Hanlon, Roger; Shashar, Nadav (2012). "A Unique Advantage for Giant Eyes in Giant Squid". Current Biology. 22 (8): 683–688. doi:10.1016/j.cub.2012.02.031. PMID 22425154.
- Bourton, Jody (7 May 2010). "Huge 'monster squid' not fearsome". BBC News. Retrieved 2 August 2015.
- Robson, G.C. (1925). "On Mesonychoteuthis, a new genus of oegopsid, Cephalopoda". Annals and Magazine of Natural History. 9 (16): 272–277. doi:10.1080/00222932508633309.
- Ellis, R. 1998. The Search for the Giant Squid. The Lyons Press.
- Griggs, Kim (2 April 2003). "Super squid surfaces in Antarctic". BBC News. Wellington. Retrieved 2 August 2015.
- "The Colossal Squid Exhibition – The Squid Files – How big is the colossal squid?". 17 December 2008. Archived from the original on 17 December 2008. Retrieved 9 March 2020.
- "The Colossal Squid". Te Papa. 21 December 2015. Retrieved 14 May 2019.
- Tapaleao, Vaimoana (11 August 2014). "Is it a boy? Te Papa gets new colossal squid". New Zealand Herald. ISSN 1170-0777. Retrieved 2 August 2015.
- "Colassal squid". Oceana International. 2023. Retrieved 12 August 2023.
- Ballance, Alison; Meduna, Veronika (16 September 2014). "Colossal squid to give up its secrets". Radio New Zealand. Retrieved 2 August 2015.
- Black, Richard (30 April 2008). "Colossal Squid's big eye revealed". BBC News. BBC.
- Remeslo, Alexander; Yukhov, Valentin; Bolstad, Kathrin & Laptikhovsky, Vladimir (1 May 2019). "Distribution and biology of the colossal squid, Mesonychoteuthis hamiltoni: New data from depredation in toothfish fisheries and sperm whale stomach contents". Deep Sea Research Part I: Oceanographic Research Papers. 147: 121–127. Bibcode:2019DSRI..147..121R. doi:10.1016/j.dsr.2019.04.008. S2CID 146043830.
- Xavier, José C.; Raymond, Ben; Jones, Daniel C. & Griffiths, Huw (19 October 2015). "Biogeography of Cephalopods in the Southern Ocean Using Habitat Suitability Prediction Models" (PDF). Ecosystems. 19 (2): 220–247. doi:10.1007/s10021-015-9926-1. S2CID 14435325.
- Sarchet, Penny (11 June 2015). "Colossal squid vs huge toothfish – clash of the deep-sea titans". New Scientist. doi:10.1080/00222933.2015.1040477. S2CID 82152308. Retrieved 2 August 2015.
- Lu, C.C. & Williams, R. (June 1994). "Contribution to the biology of squid in the Prydz Bay region, Antarctica". Antarctic Science. 6 (2): 223–229. Bibcode:1994AntSc...6..223L. doi:10.1017/s0954102094000349. S2CID 130139281.
- Cherel, Yves; Hobson, Keith A (7 August 2005). "Stable isotopes, beaks and predators: a new tool to study the trophic ecology of cephalopods, including giant and colossal squids". Proceedings of the Royal Society B: Biological Sciences. 272 (1572): 1601–1607. doi:10.1098/rspb.2005.3115. PMC 1559839. PMID 16048776.
- Rosa, Rui & Seibel, Brad A. (2010). "Slow pace of life of the Antarctic colossal squid". Journal of the Marine Biological Association of the United Kingdom. 90 (7): 1375–1378. doi:10.1017/S0025315409991494. S2CID 85063782.
- Clarke, M.R. (1980). "Cephalopoda in the diet of sperm whales of the southern hemisphere and their bearing on sperm whale biology". Discovery Reports. 37: 1–324.
- Remeslo, A. V.; Yakushev, M. R. & Laptikhovsky, V. (10 November 2015). "Alien vs. Predator: interactions between the colossal squid (Mesonychoteuthis hamiltoni) and the Antarctic toothfish (Dissostichus mawsoni)". Journal of Natural History. 49 (41–42): 2483–2491. doi:10.1080/00222933.2015.1040477. S2CID 82152308.
- Cherel, Yves & Duhamel, Guy (2004). "Antarctic jaws: cephalopod prey of sharks in Kerguelen waters". Deep Sea Research Part I: Oceanographic Research Papers. 51 (1): 17–31. doi:10.1016/j.dsr.2003.09.009.
- Jereb, P & Roper, C.F.E. (2010). Cephalopods of the world : an annotated and illustrated catalogue of cephalopod species known to date. Food and Agriculture Organization of the United Nations. ISBN 978-92-5-106720-8.
- Nilsson, Dan-Eric; Warrant, Eric J.; Johnsen, Sönke; Hanlon, Roger & Shashar, Nadav (24 April 2012). "A Unique Advantage for Giant Eyes in Giant Squid". Current Biology. 22 (8): 683–688. doi:10.1016/j.cub.2012.02.031. PMID 22425154. S2CID 6119783.
- Nilsson, Dan-E; Warrant, Eric J.; Johnsen, Sönke; Hanlon, Roger T. & Shashar, Nadav (8 September 2013). "The giant eyes of giant squid are indeed unexpectedly large, but not if used for spotting sperm whales". BMC Evolutionary Biology. 13 (1): 187. doi:10.1186/1471-2148-13-187. PMC 3854791. PMID 24010674.
- Herring, Peter J.; Dilly, P. N. & Cope, Celia (September 2002). "The photophores of the squid family Cranchiidae (Cephalopoda: Oegopsida)". Journal of Zoology. 258 (1): 73–90. doi:10.1017/S095283690200122X.
- "The eyes of the colossal squid". 29 December 2016.
- "Scientists Find that Squid Can Detect Sounds". www.whoi.edu/. Retrieved 10 April 2022.
- Partridge, Julian C. (24 April 2012). "Sensory Ecology: Giant Eyes for Giant Predators?". Current Biology. 22 (8): R268–R270. doi:10.1016/j.cub.2012.03.021. PMID 22537628. S2CID 16685449.
- "Mesonychoteuthis hamiltoni Robson, 1925". ITIS.
- "Very Rare Giant Squid Caught Alive". South Georgia Island. Archived from the original on 5 June 2010. Retrieved 2 August 2015.
- "NZ fishermen land colossal squid". BBC News. 22 February 2007. Retrieved 2 August 2015.
- Te Papa's Specimen: The Thawing and Examination Archived 25 April 2008 at the Wayback Machine. Tepapa.govt.nz. Retrieved on 30 September 2011.
- Marks, Kathy (23 March 2007). "NZ's colossal squid to be microwaved". The New Zealand Herald. Retrieved 25 September 2011.
- Black, Richard (28 April 2008). "Colossal squid comes out of ice". BBC News. Retrieved 2 August 2015.
- Ballance, Alison (14 October 2014). "Colossal Squid Revealed". Radio New Zealand. Retrieved 2 August 2015.
- "Massive squid may be just a babe". The Star. South Africa.
- "World's biggest squid reveals 'beach ball' eyes". www.terradaily.com. Wellington: AFP. 30 April 2008. Retrieved 2 August 2015.
- "Scientists Found Only The Second Intact Colossal Squid — Here's What It Looks Like". 16 September 2014. Retrieved 26 September 2014.
- "Colossal Squid". Oceana. Retrieved 10 March 2020.
- "Colossal Squid ~ MarineBio Conservation Society". Marine Bio. 18 May 2017.
Further reading
- Aldridge, A.E. (2009). "Can beak shape help to research the life history of squid?". New Zealand Journal of Marine and Freshwater Research. 43 (5): 1061–1067. doi:10.1080/00288330.2009.9626529. S2CID 85883651.
- (in Russian) Klumov, S.K. & V.L. Yukhov 1975. Mesonychoteuthis hamiltoni Robson, 1925 (Cephalopoda, Oegopsida). Antarktika Doklady Komission 14: 159–189. [English translation: TT 81–59176, Al Ahram Center for Scientific Translations]
- McSweeny, E.S. (1970). "Description of the juvenile form of the Antarctic squid Mesonychoteuthis hamiltoni Robson". Malacologia. 10: 323–332.
- Rodhouse, P.G.; Clarke, M.R. (1985). "Growth and distribution of young Mesonychoteuthis hamiltoni Robson (Mollusca: Cephalopoda): an Antarctic squid". Vie Milieu. 35 (3–4): 223–230.
External links
- "CephBase: Colossal squid". Archived from the original on 17 August 2005.
- Tree of Life web project: Mesonychoteuthis hamiltoni
- Museum of New Zealand Te Papa Tongarewa(Te Papa) Colossal Squid Specimen Information
- Museum of New Zealand Te Papa Tongarewa(Te Papa) Colossal Squid Images and Video
- Tonmo.com: Giant Squid and Colossal Squid Fact Sheet
- New Zealand Herald: Fishermen haul in world's biggest squid
- USA Today: Colossal Squid Caught in Antarctic Waters
- BBC: Super squid surfaces in Antarctic
- MarineBio: Mesonychoteuthis hamiltoni