Humboldt squid

The Humboldt squid (Dosidicus gigas), also known as jumbo squid, jumbo flying squid, pota, or diablo rojo (red devil), is a large, predatory squid living in the waters of the Humboldt Current in the eastern Pacific Ocean. It is the only species of the genus Dosidicus of the subfamily Ommastrephinae, family Ommastrephidae.

Humboldt squid typically reach a mantle length of 1.5 m (4 ft 11 in), making it the largest member of its family. They have a reputation for aggression towards humans, though this behavior may possibly only be manifested during feeding times. Like other members of the subfamily Ommastrephinae, they possess bioluminescent photophores and are capable of quickly changing body coloration (metachrosis). They notably rapidly flash red and white while hunting, earning them the name diablo rojo (Spanish for "red devil") among fishermen. These chromatophores (which belong to more than one set and are of different sizes) may rapidly cycle through colors other than red and white, flashing too quickly for the human eye to see the transitions. They have a relatively short lifespan of just 1-2 years.

They are most commonly found at depths of 200 to 700 m (660 to 2,300 ft), from Tierra del Fuego to California. This species is spreading north into the waters of the Pacific Northwest, in Oregon, Washington, British Columbia, and Alaska. They are fished commercially, predominantly in Mexico and Peru.

Description
The humboldt squid is the largest member of the Ommastrephid squids, as some individuals may grow to 2.5 m (8 ft 2 in) in mantle length and weigh up to 50 kg (100 lb). Generally, the mantle (or body) constitutes about 40% of the animal's mass, the fins (or wings) about 12%, the arms and 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.

Behavior
Humboldt squid are carnivorous marine invertebrates that move in shoals of up to 1,200 individuals. They swim at speeds up to 24 km/h (15 mph; 13 kn) propelled by water ejected through a hyponome (siphon) and by two triangular fins. Their tentacles bear 100–200 suckers, each lined with razor-sharp teeth, with which they grasp prey and drag it towards a large, sharp beak.

Although Humboldt squid have a reputation of being aggressive towards humans, some disagreement exists on this subject. Research suggests these 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. A quarter of squid stomachs analyzed contained remains of other squid. This behavior may account for a large proportion of their rapid growth. Some scientists claim the only reports of aggression towards humans have occurred when reflective diving gear or flashing lights have been present as a provocation. Roger Uzun, a veteran scuba diver and amateur underwater videographer who swam with a swarm of the animals for about 20 minutes, said they seemed to be more curious than aggressive. In circumstances where these animals are not feeding or being hunted, they exhibit curious and intelligent behavior..

Electronic tagging has shown 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 a year, although larger individuals may survive up to 2 years.

A crittercam attached to two Humboldt squid revealed that they "flash talk" with each other by changing color in certain ways, and that they can disguise themselves by shifting the color patterns in other ways. What they are communicating to each other is unknown.

Recent footage of shoals of these animals demonstrates a tendency to meet unfamiliar objects aggressively. Having risen to depths of 130–200 m (430–660 ft) below the surface to feed (up from their typical 700 m (2,300 ft) diving depth, beyond the range of human diving), they have attacked deep-sea cameras and rendered them inoperable. Humboldt squid have also been observed engaging in swarm behavior when met by the lights of submersibles, suggesting that they may follow or are attracted to light. Reports of recreational scuba divers being attacked by Humboldt squid have been confirmed. One particular diver, Scott Cassell, who has spent much of his career videotaping this species, has created body armor to protect against attacks.

Distribution
The Humboldt squid lives at depths of 200 to 700 m (660 to 2,300 ft) in the eastern Pacific (Chile, 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. Recently, the squid have been appearing farther north, as far as British Columbia. They have also ventured into Puget Sound.

Though they usually prefer deep water, between 1,000 and 1,500 squid washed up on the Long Beach Peninsula in southwest Washington in late 2004 and red algae were a speculated cause for the late 2012 beaching of an unspecified number of juvenile squid (average length 50 cm [1.5 ft]) at Monterey Bay over a 2-month period.

Ecology
The Humboldt squid's diet consists mainly of small fish, crustaceans, cephalopods, and copepods. The squid uses its barbed tentacle suckers to grab its prey and slices and tears the victim's flesh with its beak and radula. They often approach prey quickly with all 10 appendages extended forward in a cone-like shape. Upon reaching striking distance, they 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 serious lacerations to human flesh. These two longer tentacles can reach full length, grab prey, and retract so fast that almost the entire event happens in one frame of a normal-speed video camera. Each of the squid's suckers is ringed with sharp teeth, and the beak can tear flesh, although they are believed to lack the jaw strength to crack heavy bone.

Another method of hunting is pulling the prey to great depths until it faints. The Humboldt squid is also known to quickly devour larger prey when hunting in groups. Until recently, claims of cooperative or coordinated hunting in D. gigas were considered unconfirmed and without scientific merit. However, research conducted between 2007 and 2011, published in June 2012, indicates this species does engage in cooperative hunting.

Scientists suspect the recent expansion of the squid's range north along the West Coast of the U.S. is the result of overfishing of longer-lived apex predators.

Reproduction
Female squids lay gelatinous egg masses that are almost entirely transparent and float freely in the water column. The size of the egg mass correlates with the size of the female that laid it; large females can lay egg masses up to 3-4 m in diameter, while smaller females lay egg masses only about 1 m in diameter. Records of egg masses are extremely sparse because they are rarely encountered by humans, but from the few masses found to date, the egg masses seem to contain anywhere from 5000 to 4.1 million eggs, depending on size.

Fishing
Com­mer­cially, this species has been caught to serve the Eu­ro­pean com­mu­nity mar­ket (mainly Spain, Italy, France, and Ire­land), Rus­sia, China, Japan, South­east Asia, and in­creas­ingly North and South Amer­i­can mar­kets.

Fish­er­men catch squid at night. Lights from the fish­ing boats re­flect brightly on the plank­ton, which lure the squid to the sur­face to feed. Since the 1990s, the most im­por­tant areas for land­ings of Hum­boldt squid are Chile, Mex­ico, and Peru (122–297, 53–66, and 291–435 thou­sand tonnes, re­spec­tively, in the pe­riod 2005–2007).

Hum­boldt squid are known for their speed in feast­ing on hooked fish, sharks, and squid, even from their own species and shoal. Nu­mer­ous ac­counts have the squid at­tack­ing fish­er­men and divers in the area. Their col­or­ing and ag­gres­sive rep­u­ta­tion have 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.

Changes in migration patterns
Hum­boldt squid are gen­er­ally found in the warm Pa­cific wa­ters off the Mex­i­can coast; stud­ies pub­lished in the early 2000s in­di­cated an in­crease in north­ern mi­gra­tion. The large 1997–98 El Niño event trig­gered the first sight­ings of Hum­boldt squid in Mon­terey Bay. Then, dur­ing the minor El Niño event of 2002, they 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 no year-round Hum­boldt squid pop­u­la­tions are in these lo­ca­tions. This change in mi­gra­tion is sug­gested to be due to warm­ing wa­ters dur­ing El Niño events, but other fac­tors, such as a de­crease in upper trophic level preda­tors that would com­pete with the squid for food, could be im­pact­ing the mi­gra­tion shift, as well.

Humboldt squid and ocean acidification
A 2008 study pub­lished in the Pro­ceed­ings of the Na­tional Acad­emy of Sci­ences of the United States of Amer­ica pre­dicts that by the end of the 21st 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 they can take up oxy­gen at higher rates.

A more re­cent study, how­ever, pro­vides em­pir­i­cal and the­o­ret­i­cal ev­i­dence that squid me­tab­o­lism will be un­af­fected by ocean acid­i­fi­ca­tion.

In popular media
In 2009, the Hum­boldt squid was fea­tured in the final episode of the BBC's Last Chance to See, with Stephen Fry and Mark Car­war­dine. The episode was about blue whales, but the pre­sen­ters in­ter­viewed fish­er­men who talked about the ex­plod­ing di­a­blo rojo pop­u­la­tion in the Sea of Cortez and human at­tacks, and showed a squid try­ing to take a bite of a pro­tec­tively clad forearm.

A shoal of Hum­boldt squid are the main an­tag­o­nists of the 2013 novel Below, by Ryan Lock­wood.

In the 2015 novel Strands of Sor­row by John Ringo, Hum­boldt squid are de­picted in the Pro­logue.

In 2016, the Hum­boldt squid fea­tured in three tele­vi­sion shows. The first, Man Eat­ing Super Squid: A Mon­ster Invasion, pre­miered on the Na­tional Ge­o­graphic Wild chan­nel and ex­plored var­i­ous at­tacks by Hum­boldt squid in Mex­ico. In the show, the Hum­boldt squid is re­ferred to as a real-life kraken and as "a global threat".

The sec­ond show to fea­ture the Hum­boldt squid re­cently is River Mon­sters: Devil of the Deep, where an­gler and TV show host Je­remy Wade sets off to the Sea of Cortez to in­ves­ti­gate strange at­tacks on fish­er­men. Je­remy dis­cov­ers that the fish­er­men were in fact at­tacked by Hum­boldt squid and that the Hum­boldt squid have now moved on from the Sea of Cortez south to­wards the coast of Peru. After join­ing a local fish­ing crew, Je­remy Wade catches mul­ti­ple Hum­boldt squid off the coast of Peru.

In Fish­ing Impossible shown on British TV in 2016, the team travel 10 hours out into the Pa­cific Ocean and put on div­ing suits re­in­forced with chain mail to pro­tect them­selves, as they plan to cap­ture a Hum­boldt squid by hand. How­ever, bad weather pre­vents them from div­ing for the squid.

In 2016, Hum­boldt squid were fea­tured on BBC Earth's Blue Planet II where the Hum­boldt's can­ni­bal­is­tic pack hunt­ing was cap­tured on film for the first time.

A Hum­boldt Squid is a minor an­tag­o­nist in the 2016 film Find­ing Dory where it chases and at­tempts to eat the main char­ac­ters. This squid is pre­sented as much larger than its real-life coun­ter­parts, eas­ily de­stroy­ing a ship­ping con­tainer which it seems to barely fit in­side.

In an­other film, fish­er­men re­port, among other things, that a fish­er­man was caught in the abyss by a squid. And an­other fish­er­man was bit­ten by the squid on his skull, break­ing his skull.