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[[File:Squid-full.jpg|thumb|Dead colossal squid in New Zealand]] | [[File:Squid-full.jpg|thumb|Dead colossal squid in New Zealand]] | ||
The '''colossal squid''' (''Mesonychoteuthis hamiltoni'', from Greek ''mesos'' (middle), ''onycho'' (claw, nail), and ''teuthis'' (squid)), sometimes called the '''Antarctic squid''', is believed to be the largest squid species in terms of mass. It is the only known member of the genus ''Mesonychoteuthis''. It is known from only a few specimens, and current estimates put its maximum size at 12–14 m (39–46 ft) long and weighing possibly up to 750 kg (1,650 lb), based on analysis of smaller and immature specimens, making it the largest known invertebrate. | The '''colossal squid''' (''Mesonychoteuthis hamiltoni'', from Greek ''mesos'' (middle), ''onycho'' (claw, nail), and ''teuthis'' (squid)), sometimes called the '''[[Antarctic]] squid''', is believed to be the largest squid species in terms of mass. It is the only known member of the genus ''Mesonychoteuthis''. It is known from only a few specimens, and current estimates put its maximum size at 12–14 m (39–46 ft) long and weighing possibly up to 750 kg (1,650 lb), based on analysis of smaller and immature specimens, making it the largest known invertebrate. | ||
==Morphology== | ==Morphology== | ||
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The squid's known range extends thousands of kilometers 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]]. | The squid's known range extends thousands of kilometers 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]]. | ||
Little is known about the life of this creature, but it is believed to feed on prey such as chaetognatha, large fish such as the | Little is known about the life of this creature, but it is believed to feed on prey such as chaetognatha, large fish such as the Patagonian toothfish, and other squid in the deep ocean using bioluminescence. 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, 71 showed clear signs of attack by colossal squid. The colossal squid is thought to have a slow metabolic rate, needing only around 30 grams (1.1 oz) of prey daily for an adult with a mass of 500 kilogram (1102 lbs). 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. | ||
Based on capture depths of a few specimens, and beaks found in [[sperm whale]] stomachs, the adult colossal squid ranges at least to a depth of 2.2 km (7,200 ft), and juveniles can go as deep as 1 km (3,300 ft). It is believed to be sexually dimorphic, with mature females generally being much larger than mature males, as is common in many species of invertebrates. | Based on capture depths of a few specimens, and beaks found in [[sperm whale]] stomachs, the adult colossal squid ranges at least to a depth of 2.2 km (7,200 ft), and juveniles can go as deep as 1 km (3,300 ft). It is believed to be sexually dimorphic, with mature females generally being much larger than mature males, as is common in many species of invertebrates. | ||
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The squid's method of reproduction has not been observed, although some data on their reproduction can be inferred from anatomy. Since males lack an organ called a hectocotylus (an arm used in other cephalopods to transfer a spermatophore to the female), they probably use a penis instead, which would be used to directly implant sperm into females. | The squid's method of reproduction has not been observed, although some data on their reproduction can be inferred from anatomy. Since males lack an organ called a hectocotylus (an arm used in other cephalopods to transfer a spermatophore to the female), they probably use a penis instead, which would be used to directly implant sperm into females. | ||
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 [[Antarctica|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. Many other animals also feed on colossal squid, including beaked whales (such as the southern bottlenose whale), pilot whales, [[southern elephant seal]]s, | 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 [[Antarctica|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. Many other animals also feed on colossal squid, including beaked whales (such as the southern bottlenose whale), pilot whales, [[southern elephant seal]]s, Patagonian toothfish, [[sleeper shark]]s (''Somniosus antarcticus''), and albatrosses (e.g., the wandering and sooty albatrosses). However, beaks from mature adults have only been recovered from large predators (i.e. sperm whales and sleeper sharks), while the other predators only eat juveniles or young adults. | ||
==History of sightings== | ==History of sightings== | ||
[[File:Colossal-Squid.jpg|thumb|Dead colossal squid on a fishing line]] | [[File:Colossal-Squid.jpg|thumb|Dead colossal squid on a fishing line]] | ||
The species was first discovered in the form of two tentacles found in the stomach of a sperm whale in 1925. | The species was first discovered in the form of two tentacles found in the stomach of a sperm whale in 1925. In 1981 a Russian trawler in the [[Ross Sea]], off the coast of [[Antarctica]], caught a large squid with a total length of 4 m (13 ft), which was later identified as an immature female of ''M. hamiltoni''. 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 (8.2 ft).[16] This specimen shows that colossal squids may grow larger than 500 kg (1,100 lb), possibly up to 750 kg (1,650 lb). | ||
In 2005 a specimen was captured at a depth of 1,625 m (5,331 ft) while taking a toothfish from a longline off South Georgia Island. Although the mantle was not brought aboard, the mantle length was estimated at over 2.5 m (8.2 ft), and the tentacles measured 2.3 m (7.5 ft). The animal is thought to have weighed between 150 and 200 kg (330 and 440 lb). | In 2005 a specimen was captured at a depth of 1,625 m (5,331 ft) while taking a toothfish from a longline off South Georgia Island. Although the mantle was not brought aboard, the mantle length was estimated at over 2.5 m (8.2 ft), and the tentacles measured 2.3 m (7.5 ft). The animal is thought to have weighed between 150 and 200 kg (330 and 440 lb). | ||
The largest recorded specimen was captured in 2007 by a New Zealand fishing boat off Antarctica. It was initially estimated to measure 4.5 m (15 ft) in length and weigh 450 kg (990 lb). The squid was taken back to New Zealand for scientific study. | The largest recorded specimen was captured in 2007 by a New Zealand fishing boat off Antarctica. It was initially estimated to measure 4.5 m (15 ft) in length and weigh 450 kg (990 lb). The squid was taken back to New Zealand for scientific study. A study on the specimen later showed its actual weight was 495 kg (1,091 lb), but it only measured 4.2 m (14 ft) in total length as a result of the tentacles' shrinking post mortem. | ||
==Largest known specimen== | ==Largest known specimen== | ||
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The beak is considerably smaller than some found in the stomachs of sperm whales, suggesting other colossal squid are much larger than this one. The eye is 27 cm (11 in) wide, with a lens 12 cm (4.7 in) across. This is the largest eye of any known animal. These measurements are of the partly collapsed specimen; when living the eye was probably 30 to 40 cm (12 to 16 in) across. Inspection of the specimen with an endoscope revealed ovaries containing thousands of eggs. | The beak is considerably smaller than some found in the stomachs of sperm whales, suggesting other colossal squid are much larger than this one. The eye is 27 cm (11 in) wide, with a lens 12 cm (4.7 in) across. This is the largest eye of any known animal. These measurements are of the partly collapsed specimen; when living the eye was probably 30 to 40 cm (12 to 16 in) across. Inspection of the specimen with an endoscope revealed ovaries containing thousands of eggs. | ||
==External links== | |||
* [https://www.kolossal.org/ Kolossal - a nonprofit dedicated to the Colossal Squid] | |||
[[Category:Animals of Westarctica]] | [[Category:Animals of Westarctica]] | ||