| Humboldt squid | |
|---|---|
 | |
| A Humboldt squid swimming aroundROVTiburon, possibly attracted to its lights | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Order: | Oegopsida |
| Family: | Ommastrephidae |
| Subfamily: | Ommastrephinae |
| Genus: | Dosidicus Steenstrup, 1857 |
| Species: | D. gigas |
| Binomial name | |
| Dosidicus gigas | |
| Synonyms[3] | |
TheHumboldt squid (Dosidicus gigas), also known asjumbo squid orjumbo flying squid, is a large, predatorysquid living in the easternPacific Ocean. It is theonly known species of the genusDosidicus of thesubfamilyOmmastrephinae,familyOmmastrephidae.[4]
Humboldt squid typically reach amantle length of 1.5 m (5 ft), making the species the largest member of its family, andone of the largest species of squid. They are most commonly found at depths of 200 to 700 m (660 to 2,300 ft), fromTierra del Fuego toCalifornia. This species is currently spreading north into the waters of thePacific Northwest, inOregon,Washington,British Columbia, andAlaska. Like other members of the subfamily Ommastrephinae, they possesschromatophores which enable them to quickly change body coloration, known as 'metachrosis' which is the rapid flash of their skin from red to white. They have a relatively short lifespan of just 1–2 years.
This species is the most important squid worldwide for commercialfisheries, with the catch predominantly landed inChile,Peru andMexico; however, a 2015 warming waters fishery collapse in theGulf of California remains unrecovered.[5][6] They have a reputation foraggression toward humans, although this behavior may only occur during feeding times.
This species is most often known asjumbo squid in English, but has also been calledjumbo flying squid orHumboldt squid, with the last name most popular in naturalist sources.[7] The name Humboldt refers to theHumboldt Current, off the southwestern coast of South America, where it was first collected.[8] A general name for this species inSpanish in Latin America iscalamar gigante.[9][10] Local names for it arejibia in Chile[11] orpota in Peru.[12] They notably rapidly flash red and white when captured, earning them the nicknamediablo rojo (meaning 'red devil') among local fishermen inBaja California, Mexico.[13]
The existence of this creature wasfirst described to the scientific world by the Chilean priest andpolymathJuan Ignacio Molina in 1782, who named itSepia tunicata,Sepia being thetype genus ofcuttlefish. It was subsequently moved by the French naturalistAlcide d'Orbigny, who renamed itLoligo gigas in 1835, but another French naturalist,Claude Gay, obtained some specimens from Chile and sent them to theMuséum national d'Histoire naturelle in Paris, where it was determined that the species did not belong withLoligo either. In 1857 the Danish zoologistJapetus Steenstrup proposed the new genusDosidicus to house the species, where it remains.[14] The German zoologist George PfeffersynonymizedD. eschrichtii withD. gigas in 1912.[14][15]
The fossil speciesDosidicus lomita is represented by fossils ofstatoliths from thePlioceneLomita Marl ofCalifornia, marking the earliest known occurrence of the genus.[16]
The Humboldt squid is the largest of theOmmastrephid squids, as some individuals may grow to 1.5 m (5 ft) inmantle length[17][18] and weigh up to 50 kg (110 lb).[15] They appear to besexually dimorphic: on average the females mature at larger sizes than the males.[19] Generally, the mantle (or body, which includes thefins or wings) constitutes about 56–62% of the animal's mass, thearms and tentacles about 11–15%, the head (includingeyes andbeak) about 10–13%, the outer skin (cuticle) 2.5–5.0%, thehepatopancreas (liver analogue) 4.2–5.6%, with the rest made up of the other inner organs. Thegonads consist of 1.5–15.0% of the total mass. Thegladius (the single inner 'bone') is 0.7–1.0%. Precise ratios depend on the age, sex and sizes of the individual squid.[20]
They arepropelled by water ejected through a hyponome (siphon) and by two triangular fins.[21] The Humboldt's twotentacles are elastic and can lash out with remarkable speed to grab hold of prey, holding it fast with the help of a wealth of suckers on each tentacle. Each sucker includes an inner ring of teeth. After grabbing the prey, the tentacles then retract and the prey is drawn toward a large, razor-sharp beak.[21]
Humboldt squid are carnivorous marine invertebrates that move inshoals of up to 1,200 individuals. They swim at speeds up to 24 km/h (15 mph; 13 kn).[22]
Electronic tagging has shown Humboldt squid undergodiel vertical migrations, which bring them closer to the surface from dusk to dawn.[23] Humboldt squid are thought to have a lifespan of about a year, although larger individuals may survive up to 2 years.[15]
Crittercams attached to two or three Humboldt squid revealed the species has two modes of color-generating (chromogenic) behavior:
Although these two chromogenic modes are not known in other squid species, other species do have functionally similar behaviors.[24][25]
The Humboldt squid lives at depths of 200 to 700 m (660 to 2,300 ft) in the easternPacific (Notably inChile andPeru), ranging fromTierra del Fuego north toCalifornia. Recently, the squid have been found as far north asBritish Columbia.[8] They have also ventured intoPuget Sound.[26]
Although they usually prefer deeper water, between 1,000 and 1,500 squid washed up on theLong Beach Peninsula in southwest Washington in late 2004[27] andred algae were a speculated cause for the late 2012 beaching of an unspecified number of juvenile squid (average length 50 cm or 1.5 ft) atMonterey Bay over a 2-month period.[28]
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 large1997–1998 El Niño event triggered the first sightings of Humboldt squid inMonterey 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 uppertrophic level predators that would compete with the squid for food, could be impacting the migration shift, as well.[8][29]
A 2017 Chinese study found thatD. gigas is affected by El Niño events in the waters off Peru. The squid populations cluster into groups less, and are thus more dispersed, during El Niño events. Additionally, during warm El Niño conditions and high water temperature the waters off Peru were less favourable forD. gigas.[30]
The Humboldt squid's diet consists mainly of smallfish (lanternfish, in particular),crustaceans,cephalopods, andcopepods.[31] The squid uses its barbed tentacle suckers to grab its prey and slices and tears the victim's flesh with its beak andradula. 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 hooks, grabbing their prey and pulling it back toward 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.[21] The squid are known for their speed at eating; they feast on hooked fish, stripping them to the bone before fishermen can reel them in.[21]
Their behavior while feeding often includescannibalism and they have been seen to readily attack injured or vulnerable squid in their shoal. A quarter of squid stomachs analyzed contained remains of other Humboldt squid.[32] This behavior may account for a large proportion of their rapid growth.[21][33] An investigation of the stomach contents of over 2,000 squid caught outside of theExclusive Economic Zone off the coasts of Chile found that cannibalism was likely the most important source of food. Over half had the beaks ofD. gigas in their stomachs, andD. gigas was the most common prey item. The researchers do note, however, that squid jigged in the light field around the survey vessel showed much more cannibalism.[19]
Until recently, claims ofcooperative or coordinated hunting inD. gigas were considered unconfirmed and without scientific merit.[34] However, research conducted between 2007 and 2011 indicates this species does engage in cooperative hunting.[35][additional citation(s) needed]
Females 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 (10–13 ft) in diameter,[36] while smaller females lay egg masses about one meter (3+1⁄4 ft) 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 5,000 to 4.1 million eggs, depending on size.[37]
Numerous accounts have the squid attacking fishermen and divers.[38] Their coloring and aggressive reputation have earned them the nicknamediablos rojos (red devils) from fishermen off the coast of Mexico, as they flash red and white when struggling on a line.[13]
Although Humboldt squid have a reputation of being aggressive toward humans, some disagreement exists on this subject. Research suggests these squid are aggressive only while feeding; at other times, they are quite passive.[32] Some scientists claim the only reports of aggression toward 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.[39] In circumstances where these animals are not feeding or being hunted, they exhibit curious andintelligent behavior.[40]
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 ofrecreational scuba divers being attacked by Humboldt squid have been confirmed.[41][42]
Commercially, this species has been caught to serve the European market (mainly Spain, Italy, France, and Ireland), Russia, China, Japan, Southeast Asia, and increasingly North and South American markets.[citation needed]
It is the most popular squid in the world, as of 2019 a third of all squid hunted is this species.[44]
The method used by bothartisanal fishermen as well as more industrial operations to catch the squid is known asjigging.[10][19] Squid jigging is a relatively novel method of fishing in the Americas.[45] It is done byhandlining by artisanal fishermen, or by using mechanical jiggers.[10][46] Jigging involves constantly jerking the line up and down to simulate prey; a reel with an elliptical or oval-shaped hub helps with this.[46][47] Squid jigging is done at night, using bright overhead lights from the fishing boats which reflect brightly off the jigs andplankton in the seawater, luring the squid toward the surface to feed. The seem to prefer striking at the jigs from adjacent shadowed areas, especially the shade under the hull of the boat.[45][46] Often as many as 8 to 12 jigs are onsnoods on one handline, and many more are used on automated squid jigging systems.[46] The lines are hung anywhere from 10 to 100 m (33 to 328 ft) in depth, depending on the power of the lamps used.[46][47]
The jigs are calledpoteras in Spanish. Different types of jigs are suitable for either handlining or for mechanical jigging for jumbo squid. They are made frombakelite and/orstainless steel, and measure 75 to 480 mm (3 to 19 inches) in length. Jigs can have a single axis, or one to three 'arms' (ejes) which wave around when the jig is jerked,[10] and a series of crowns (coronas) of bristle-like wire-hooks, the hooks lacking barbs, making up the tail.[10][46] The body of the jigs is usuallyphosphorescent,[10] but glow-in-the-darklures may be attached to them.[47] Jigs are extremely selective, not only can one type of jig attract only squid, often the jigs can select for a single species of squid, and even specific sizes of that species. The more arms and crowns, the more hooks, the higher the chances of snagging and actually reeling in the squid.[10]
Since the 1990s, the most important areas for landings of Humboldt squid are Chile (122–297 thousand tonnes or 134–327 thousand short tons), Mexico (53–66 thousand tonnes or 58–73 thousand short tons), and Peru (291–435 thousand tonnes or 100–480 thousand short tons), in the period 2005–2007.[19]
Based on 2009 national fisheries data, in Mexico this species represents 95% of the total recorded catch of squid. 88% of this is caught off the coasts ofSonora andBaja California Sur.[9]
Because the flesh of the animals is saturated withammonium chloride, which keeps them neutrally buoyant in seawater, the animal tastes unpleasantly salty, sour, and bitter when fresh (somewhat akin tosalmiak). To make the squid more palatable for the frozen squid market, freshly caught Humboldt squid are commercially processed by first mechanically tenderizing them, dropping them in icy water with 1% mixture oflactic andcitric acid for three hours, then washed, then soaked in another vat with a 6%brine solution for three hours. An alternate method for home cooks to neutralize the unpleasant taste also exists.[11]
Compared to other types of seafood, Humboldt squid is inexpensive along their native South American Pacific coastline, retailing around US$0.30/kg in Peru, and about US$2.00/kg in Chile, in the early 2010s.[11][12]
In Chile the squid is eaten inchupes andpaila marina.[11] In Peru, the practice of makingceviche from cheap squid began in the poorer parts ofLima when the meat became available in the 1990s, and has since spread toCuzco. It is sold on the street in food carts, as well ascevicherias, restaurants dedicated to this cuisine.[12] In the United States it is made into 'squid steaks'.
In Chile, at the end of the 50s and early 60s, electrophysiological and neurophysiological studies were carried out by theMontemar Institute of Marine Biology,[48][49][50][51][52] in Valparaiso, Chile. The remarkable size of thesquid giant axon andsquid giant synapse possessed by the Humboldt squid made it ideal for manipulative work in the laboratory.[48] This research was chronicled in the documentaryMontemar y Los Laberintos de la Memoria [Montemar and The Labyrinths of Memory]. 2016.
A 2008 study predicted thatocean acidification will lower the Humboldt squid's metabolic rate by 31% and activity levels by 45% by the end of the 21st century. It also predicted that the squid would not be able to spend as much of the day in deeper and colder waters, as a larger proportion of the ocean would fall into theoxygen minimum zone.[53]
A more recent study, however, provided empirical and theoretical evidence that the squid metabolism was unaffected by ocean acidification.[54]
The Humboldt squid was featured in the final episode of the 2009BBC'sLast Chance to See withStephen Fry andMark Carwardine. The episode was about blue whales, but the presenters interviewed fishermen who talked about the "exploding"diablo rojo population in theSea of Cortez and human attacks, and showed a squid trying to take a bite of a protectively clad forearm.
In 2016 the squid featured in various television shows.Man Eating Super Squid: A Monster Invasion on the National Geographic Wild channel explored various attacks by Humboldt squid in Mexico. In the show, the squid is referred to as a real-lifekraken and as "a global threat".[55] The second show wasRiver Monsters: Devil of the Deep, where show hostJeremy Wade talks to fishermen allegedly attacked by the squid in the Sea of Cortez, and then catches the animals off the coast of Peru.[56] In the BritishFishing Impossible [wd],mail-clad divers plan to capture a Humboldt squid by hand in the Pacific Ocean, but are prevented from doing so due to bad weather.[57] InBBC Earth'sBlue Planet II the squid's cannibalistic pack hunting was captured on film for the first time.[58]
