Dosidicus gigas, otherwise known as the Humboldt or jumbo squid, inhabits the Eastern Pacific Ocean from northern California to southern Chile. This squid is believed to have both small scale migration within the Gulf of California, from the Baja peninsula to Guaymas Basin. It may also have a large scale migration as part of its life cycle, but little about their large scale migration is known.
In the past, Dosidicus gigas was only rarely spotted off of central California, but evidence now indicates that this squid has expanded its range northward through California following El Nino events which warmed northern waters. Humboldt squid have been spotted as far north as Alaska. Similarly, it has also expanded its range to southern Chile during warm water intrusions. (Lovgren, 2003; MarineBio.org, 2008; Markaida, et al., 2003; Zeldberg, et al., 2007)
Dosidicus gigas occupies vast habitat that ranges in depths from >250m during the day to near surface depths at night. This diel migration, or vertical migration between the day and night, is also characteristic of many prey species of Dosidicus gigas, so it is thought that the squid performs this vertical migration in order to follow its prey.
Although waters around and below 250 meters deep are often relatively hypoxic, Dosidicus gigas can apparently tolerate the low dissolved oxygen levels by suppressing its rate of oxygen consumption.
Dosidicus gigas is the largest squid in the family Ommastrephidae. These squid can weigh up to 50kg and have a mantle length of up to 2m. This species, like other squid, move via jet propulsion by moving water through their mantle as well as by fin movement.
Dosidicus gigas has a long and thick mantle, tentacles containing 100-200 hooked suckers each, and a powerful beak to tear through prey. They also have well developed eyes, and chromatophore cells like other cephalopods, which allow the squid to change color and flash to communicate. Their nickname "red devil" comes from the fact that when caught by fisherman and brought to the surface, these squid turn a bright red color. (MarineBio.org, 2008; Olsen and Young, 2007)
Dosidicus gigas has direct development and grows very quickly; its lifespan is only about one year. The embryo develops for 6-9 days then hatches into a paralarval stage called a rhynchoteuthion when it is about 1mm. This paralarva (1-10mm mantle length) is distinguished by having its two tentacles fused into a proboscis, and survives in the upper planktonic layer. There it grows to become a juvenile (15-100mm mantle length). The juvenile then morphs into a subadult (150-350mm mantle length) before finally developing into an adult. During these developmental stages, the morphology and feeding habits of the squid changes.
Growth is fastest during the first four months of development. Dosidicus gigas has the highest juvenile development rates of all of the squid in its family. Juveniles can obtain a mantle length of up to 100mm by 45-55 days old. (Nigmatullin, et al., 2001; Staaf, et al., 2008)
Dosidicus gigas only has one reproductive cycle during their lifetime, so they are known as monocyclic. Squids mate in a head to head position. Fertilization takes place inside the female. The two squids intertwine tentacles and the male places its spermatophores inside the buccal (oral) membrane of the female.
Because these squid spend much of their time below 250m, details about courtship is unknown, but sometimes mating has been observed at or near the surface. Given their well-developed brain, eyes, and chromatophore arrays, it's likely that some kind of courtship displays and behavior occur in this species, but it has not been documented. (Nigmatullin, et al., 2001)
Dosidicus gigas is believed to have only one reproductive cycle during their lifetime. Squids mate in a head to head position. Fertilization takes place inside the female. The two squids intertwine tentacles and the male places its spermatophores inside the buccal (oral) membrane of the female.
Females produce floating egg masses protected by a layer of jelly. The only documented mass found in the wild contained an estimated 0.6-2.0 million eggs (Staaf et alia, 2008). Examination of gravid females suggests that each female can produce 3-20 such masses.
Based on collections of newly hatched individuals, spawning is believed to occurs throughout the year, with peaks from October through January in the Southern Hemisphere. (MarineBio.org, 2008; Nigmatullin, et al., 2001; Staaf, et al., 2008)
While fertilization occurs inside the female, once she lays the loose jelly-like egg batch there is no further parental investment. (Nigmatullin, et al., 2001)
The longevity of this squid is about one year on average. Larger individuals can live up to 2 years. In captivity, captured Humboldt squid rarely live past a few days. (Lovgren, 2003; Nigmatullin, et al., 2001)
Dosidicus gigas has a well developed brain, mantle, and fins. Juveniles cohorts are the most active, as they swim in schools of 20-40 individuals 20-50m below the surface and may even jump out of the water in order to avoid predators. Subadults are less active and either hunt alone or congregate into hunting schools of 20-200 individuals. Adults are least abundant in schools, with only 2-12 adults in a school. Adults can be aggressive. Cannibalism has been observed, but only when one of the squid was caught on a fishing line. While there may be competition with other squid species such as Sthenoteuthis oualaniensis for food, Dosidicus gigas has been observed schooling with this other squid.
Jumbo squid are known to show diel vertical migration, swimming deep during the day and approaching the surface at night. They also probably have small and large-scale horizontal migration patterns, but very little is known of the details. Small scale migration within the Gulf of California, from the Baja peninsula to Guaymas Basin has been documented. Abundance of newly-hatched young suggest that there are spawning areas in the Gulf of California and the around the Costa Rican Dome.
Given their well-developed brain, eyes, and chromatophores, courtship and other social communication is likely, but has not been documented. (MarineBio.org, 2008; Nigmatullin, et al., 2001; Staaf, et al., 2008)
It is unknown if a Humboldt squid has a home range. (MarineBio.org, 2008)
Like most other cephalopods, Dosidicus gigas has an extremely advanced eye and has chromatophores in the skin. Because they can travel in groups of up to 1200 individuals, they use visual cues to interact with one another. On possible example in Dosidicus gigas is that individuals can make their entire body flash red, apparently when angered or irritated. This warns nearby organisms that the individual is aggressive enough to attack if provoked. Dosidicus gigas uses its tentacles to feel something that it is curious about, such as a human diver. (MarineBio.org, 2008; Nigmatullin, et al., 2001; Olsen and Young, 2007)
Dosidicus gigas is an active predator and pursues its prey. It uses suckers on its tentacles to capture prey animals and bring them towards its beak. Juveniles eat copepods and pelagic shrimp, and as Dosidicus gigas grows, its diet shifts more towards fish and other cephalopods. During their nightly vertical migration to the surface waters, adult Dosidicus gigas feed mainly on lanternfish, but will feed on a variety of other pelagic species including other fish, squids, and octopuses. Adults have been known to eat juveniles of their own species. (MarineBio.org, 2008; Nigmatullin, et al., 2001)
Juvenile Dosidicus gigas are preyed upon by juvenile carnivorous fishes, including small tunas, other squid (Sthenoteuthis oualaniensis) and gulls. Once they reach 150mm to around 250mm in length, they start to become preyed upon by dorado, large tunas (and related species), as well as large sharks, swordfish and striped marlins, fur seals, sperm whales and short-finned pilot whales.
Dosidicus gigas can alter its coloration to match its environment, and squirt ink from its ink sac in order to confuse or temporarily blind would-be predators. This squid has been known to “fly” by propelling themselves out of the water to escape attack. (MarineBio.org, 2008; Nigmatullin, et al., 2001)
Dosidicus gigas is a large and abundant pelagic species, and can play a very important role both as food for predators and as a mid-level carnivore. The species has very high reproductive potential, and when conditions are right, populations of the species can increase very fast.
There are also 9-12 parasitic worm species (trematodes, nematodes and cestodes) that infect the larval Dosidicus gigas, as well as a type of ciliate parasite genus found in this squid. (Nigmatullin, et al., 2001)
The Dosidicus gigas fishery is one of the largest fisheries in the Central Eastern Pacific (measured by annual tonnage caught), and is the largest cephalopod fishery in the world.
Dosidicus gigas is useful for a wide variety of research. For example, the apparent change in the distribution of this species is useful for climate change studies. The squid is also food for many recreational and commercial fisheries like tunas and billfishes. (Olsen and Young, 2007)
The food demands of Dosidicus gigas, puts them in competition with humans for some commercially harvested fish or other squid. With climate change occurring and shifting their range, Dosidicus gigas may begin to affect fish stocks in the northern Pacific.
These squid are large enough to be a potential danger to human divers. (Olsen and Young, 2007)
Dosidics gigas was originally discovered in 1835 and named Dosidicus gigas. Later that century the genus Dosidicus was created, and finally in 1912, the similarities between the jumbo squid and the other species led to the taxonomic name change to Dosidicus gigas. (Nigmatullin, et al., 2001)
Jessica Kurth (author), Rutgers University, Michael Garzio (author), Rutgers University, David Howe (editor, instructor), Rutgers University .
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
an animal that mainly eats meat
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
A substance that provides both nutrients and energy to a living thing.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
fertilization takes place within the female's body
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
makes seasonal movements between breeding and wintering grounds
imitates a communication signal or appearance of another kind of organism
eats mollusks, members of Phylum Mollusca
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
generates and uses light to communicate
an animal that mainly eats fish
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
mature spermatozoa are stored by females following copulation. Male sperm storage also occurs, as sperm are retained in the male epididymes (in mammals) for a period that can, in some cases, extend over several weeks or more, but here we use the term to refer only to sperm storage by females.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.
uses sight to communicate
young are relatively well-developed when born
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
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