Humboldt Squid
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| Humboldt Squid | ||||||||||||||||
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 Humboldt Squid photographed
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| Dosidicus gigas (Orbigny, 1835) |
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The Humboldt Squid (Dosidicus gigas), also known as Jumbo Squid, Jumbo Flying Squid, or Diablo Rojo (Red Devil), is a large, aggressive predatory squid found in the waters of the Humboldt Current in the Eastern Pacific Ocean. They are most commonly found at depths of 200–700 metres (660–2,300 ft), from Tierra del Fuego to California. Recent findings suggest the range of this species is spreading north into the waters of Oregon, Washington, British Columbia, and Alaska.[1][2] 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[3] and have ventured into Puget Sound.[4]
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[edit] Behavior and general characteristics
Humboldt Squid are carnivorous marine invertebrates that move in shoals of up to 1200 individuals. 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. Their tentacles bear suckers lined with sharp teeth with which they grasp prey and drag it towards a large, sharp beak.
Humboldt Squid are thought to have a lifespan of only about one year (although some researchers believe they may survive up to four years). They may grow to 2 metres (7 ft) and weigh 45 kilograms (100 lb), growing at an astounding rate. They can rapidly change their skin colour from deep purplish red to white using chromatophores (specialized skin cells) in what some researchers believe is a complex communication system.[citation needed] Experts have also stated that the invertebrates hunt for their prey of small fish and krill, in a cooperative fashion, which would be the first observation of such behaviour.[5] 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. There have been reports of these squid attacking divers and fishermen in the Sea of Cortez.[6] The shallowest depths of Humboldt Squid's daytime habitat are only within reach of the extremes of saturation diving, so little is known of what they do during the day.
Recent research suggests that the squid are only aggressive while feeding. At other times, they are quite passive. 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.[7][8]
[edit] Body characteristics
Generally, the tube (or body) constitutes about 40% of the animal's mass, the fin (or wing) about 12%, the tentacles about 14%, the outer skin about 3%, the head (including eyes and beak) about 5%, with the balance (26%) made up of the inner organs. In circumstances where these animals are not feeding or being hunted, they exhibit curious and intelligent behavior.[9]
They often approach prey quickly with all ten appendages extended forward in a cone-like shape. Upon reaching striking distance, they will open their eight swimming and grasping arms, and extend two long tentacles covered in sharp 'teeth,' grabbing their prey and pulling it back towards a parrot-like beak, which can easily cause dramatic lacerations to human flesh. The whole instance takes place in seconds.
Recent footage of schoals of these animals demonstrates a tendency to meet unfamiliar objects aggressively. Having risen to depths of 130–200 metres (430–660 ft) below the surface to feed (up from their typical 700 meter (2,300 ft) diving depth, beyond the range of human diving), they have attacked deep-sea cameras and rendered them inoperable. Reports of recreational scuba divers being attacked by Humboldt Squid have been confirmed. One particular diver, Scott Cassell,[10] who has spent much of his career videotaping this species, has developed body armor to protect against attacks.[11] Each of the squid's suckers is ringed with sharp teeth, and the beak itself can tear flesh, although it's believed they lack the jaw strength to crack heavy bone.[7] Nevertheless, they eat their prey by grabbing it with their tentacles and biting it repeatedly with their beak. Working together, several squid are able to devour large prey very quickly.
[edit] Fishing
Commercially, this species has been caught to serve the European community market (mainly Spain, Italy and France), Russia, China, Japan, South East Asian and increasingly North and South American markets.
The squid are fished at night, when it is easier to lure them with lights used by fishermen that make the plankton the squid feed on shine, which causes the squid to rise to the surface to feed. Since the 1990s, the most important areas for landings of Humboldt Squid are northern Peru and Mexico.
There are numerous accounts of the squid attacking fishermen and divers in the area and attacks on humans are regularly seen, but only when they are being fished. Their colouring and aggressive reputation has earned them the nickname diablos rojos (red devils) from fishermen off the coast of Mexico as they flash red and white when struggling with the fishermen.
[edit] Humboldt Squid and El Niño
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. The large 1997-98 El Niño event triggered the first sightings of Humboldt Squid in Monterey Bay.[2] 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. 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. It has been suggested that this change in migration is due to warming waters during El Niño events, 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.[2]
[edit] Humboldt Squid and ocean acidification
A study conducted by members of the National Academy of Sciences of the United States of America found that by the end of this century ocean acidification will lower the Humboldt squid's metabolic rate by 31% and activity levels by 45%. This will lead the squid to have to retreat to shallower waters where it can uptake oxygen at higher levels.[12]
[edit] See also
[edit] References
- ^ Humboldt Squid Found in Pebble Beach (2003)
- ^ a b c Zeidberg, L. & B.H. Robinson 2007. Invasive range expansion by the Humboldt Squid, Dosidicus gigas, in the eastern North Pacific. PNAS 104(31): 12948–12950.
- ^ Aggressive eating machines spotted on our coast (2008)
- ^ Giant squid caught in West Seattle
- ^ Behold the Humboldt squid. Tim Zimmermann, Outside Magazine, July 2006.
- ^ Sea of Cortez, 1995
- ^ a b The Curious Case of the Cannibal Squid, Michael Tennesen, National Wildlife Magazine, Dec/Jan 2005, vol. 43 no. 1.
- ^ Squid SensitivityDiscover Magazine April, 2003
- ^ Behold the Humboldt Squid | Outside Online
- ^ DeeperBlue.net - Fanatical About FreeDiving, Scuba Diving, Spearfishing & Technical Diving
- ^ Cassell, S. Dancing with Demons. Deeper Blue, 2005-12-15
- ^ Rosa, Rui, and Brad A. Seibel. "Synergistic effects of climate-related variables suggest future physiological impairment in a top oceanic predator." Proceedings of the National Academy of Sciences 105 (2008): 20776-0780
