Colossal Squid

== Description ==
The colossal squid (Mesonychoteuthis hamiltoni ) is part of the family Cranchiidae. It is sometimes called the Antarctic squid or giant cranch squid and is believed to be the largest squid species in terms of mass. It is the only recognized member of the genus Mesonychoteuthis and is known from only a small number of specimens. 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), making it the largest-known invertebrate. Maximum total length has been estimated at 9–10 metres (30–33 ft).
== Appearance ==
The colossal squid shares features common to all squids: a mantle for locomotion, one pair of gills, and certain external characteristics like eight arms and two tentacles, a head, and two fins. In general, it is safe to describe the morphology and anatomy of the colossal squid the same way one would describe any other squid. However, there are certain morphological / anatomical 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. There are squids in other families that also have hooks, but no other squid in the family Cranchiidae.
== Distribution ==
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. Colossal squid are also sighted often near Cooperation Sea and less near Ross Sea because of its predator and competitor, the Antarctic toothfish. The region between the Weddell Sea and the western Kerguelen archipelago has been deemed a “hotspot” based on characteristics of the habitat. 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.
== Lifestyle ==
The Giant Squid is thought to have a slow paced life because of its large size and low prey requirements.
== Diet ==
Little is known about their behavior, 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. 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. 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. 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. 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.
== Reproduction ==
Little is known about the colossal squid's reproductive cycle although the colossal squid does have two distinct sexes. Many species of squid, however, develop sex-specific organs as they age and develop. 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. 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. 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. Young squid are thought to spawn near the summer time at surface temperatures of −0.9–0 °C (30.4–32.0 °F).
== Population ==
=== Population number ===
The colossal squid has been assessed as least concern on the IUCN Red List. Furthermore, colossal squid are not targeted by fishermen; rather, they are only caught when they attempt to feed on fish caught on hooks. Additionally, due to their habitat, interactions between humans and colossal squid are considered rare.
== Main References ==
https://animalia.bio/colossal-squid
https://animaldiversity.org/accounts/Mesonychoteuthis_hamiltoni/
Category:Animals
Category:Animalia
Category:Mollusca
Category:Cephalopoda
Category:Molluscs
Category:Oegopsida
Category:Cranchiidae
Category:Mesonychoteuthis
Category:Carnivores
Category:Piscivores
Category:Natatorial Animals
Category:Antarctican Animals
Category:South American Animals
Category:African Animals
Category:Animals of Australia
Category:Animals of Chile
Category:Animals of Argentina
Category:Animals of South Africa
Category:Least Concern Animals