Monday, December 20, 2010

Humboldt Squid



Humboldt Squid are carnivorous marine invertebrates that move in shoals of up to 1,200 individuals.
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They swim at speeds of up to 24 kilometres per hour (15 mph/13 kn) propelled by water ejected through a hyponome (siphon) and by two diamond shaped fins.
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Their tentacles bear suckers lined with sharp teeth with which they grasp prey and drag it towards a large, sharp beak.
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The Humboldt Squid (Dosidicus gigas), also known as Jumbo Squid, Jumbo Flying Squid, or Diablo Rojo (Spanish for Red Devil), is a large, predatory squid found in the waters of the Humboldt Current in the Eastern Pacific Ocean.
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They are most commonly found at depths of 200–700 metres (660–2,300 ft), from Tierra del Fuego to California.
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Recent findings suggest the range of this species is spreading north into the waters of Oregon, Washington, British Columbia, and Alaska.
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Though they usually prefer deep water, between 1,000 and 1,500 squid washed up on the Long Beach Peninsula in southwest Washington in the fall of 2004
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They have also ventured into Puget Sound.
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Although Humboldt Squid are generally found in the warm Pacific waters off of the Mexican coast, recent years have shown an increase in northern migration.
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The large 1997-98 El Niño event triggered the first sightings of Humboldt Squid in Monterey Bay.
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Then, during the minor El Niño event of 2002, Humboldt Squid returned to Monterey Bay in higher numbers and have been seen there year-round since then.
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Similar trends have been shown off the coasts of Washington, Oregon, and even Alaska, although there are no year-round Humboldt Squid populations in these locations.
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It has been suggested that this change in migration is due to warming waters during El Niño events.
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But other factors, such as a decrease in upper trophic level predators that would compete with Humboldt Squid for food, could be impacting the migration shift as well.
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The Humboldt squid lives at depths of 200 to 700 m (660 to 2,300 ft) in the eastern Pacific from Chile to Peru, ranging from Tierra del Fuego north to California.
 
It gets its name from the Humboldt Current in which it lives off the coast of South America.

Electronic tagging has shown that Humboldt squid undergo diel vertical migrations which bring them closer to the surface from dusk to dawn.

Humboldt Squid are thought to have a lifespan of only about one year, although larger individuals may survive up to two years.
They may grow to 1.75 metres (5.7 ft) in mantle length (ML) and weigh up to 50 kilograms (100 lb).
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They can rapidly change their skin color from deep purplish red to white using chromatophores (specialized skin cells) in what some researchers believe is a complex communication system.
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Experts have also stated that the squid hunt for their prey of small fish and krill in a cooperative fashion, which would be the first observation of such behavior in invertebrates.
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Humboldt Squid are known to hunt near the surface at night, taking advantage of the dark to use their keen vision to feed on more plentiful prey.
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Recent research suggests that Humboldt squid are only aggressive while feeding.
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At other times, they are quite passive.
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Their behavior while feeding often extends to cannibalism and they have been seen to readily attack injured or vulnerable squid of their own shoal.

This behavior may account for a large proportion of their rapid growth.
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Research has barely begun into their habits

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