Architeuthis dux

Geographic Range

Giant squid are distributed in all the oceans of the world, usually in association with continental and island slopes. Concentrations of species found range from the North Atlantic Ocean, especially Newfoundland, Norway, northern British Isles and the oceanic islands of the Azores and Madeira; the South Atlantic in southern African waters; the North Pacific around Japan, and the southwestern Pacific around New Zealand and Australia; circumglobal in the Southern Ocean. Specimens are rare from tropical and high polar latitudes.(Forch 1998)

Habitat

No one really knows where giant squid live because no one has seen one alive in its natural habitat. Only recent research has indicated where this habitat might be. It is in the deep sea, perhaps between 200 and 1000 meters in depth, and it is possibly in association with the bottom of the sea rather than in mid-water. On the other hand, specimens that have been captured in nets sometimes come from mid-water.

Work done by Dr. Ole Brix, of the University of Bergen, indicated the blood of squids does not carry oxygen very well at higher temperatures. A squid will actually suffocate in warm water. Warm water will cause a giant squid to rise to the surface and not be able to get back down. So the giant squid are probably more likely to be found in cooler water. (Forch 1998) (Banister and Campbell 1985)

Physical Description

The Architeuthidae are the largest known cephalopods, the largest known mollusks and probably the largest invertebrates ever known to exist in the oceans. Architeuthidae have been recorded as long as 60 feet in total length, most of the specimens that have been found are really in the 35-45 foot range. There are still many which range from about 20 to 30 feet in length. The total length includes the body, the head, the arms, and the two long feeding tentacles. These feeding tentacles are much longer than the rest of the body. The heaviest animals weigh about a ton, but most of the time they are a thousand pounds or less.

These giant squid also have the largest eyes out of any animal in the world. The eyes of the giant squid can be as big as a human's head. Most deep-sea animals have very large eyes so they can gather the small amounts of light that are available in the deep depths of the ocean. They might even be able to see bioluminescent light.

The Architeuthidae posses two tentacles that average about 10-12 meters in length. These tentacles have many suckers on the tips, called clubs. The tentacular clubs are narrow and have suckers, which are sub-spherical cups lined with sharp, finely serrated rings of chitin, in four longitudinal rows. These suckers cover only the inner surface of the arms and tentacles. These tentacular clubs are divided into distinct carpus, manus and dactylus. The manus has enlarged suckers along medial two rows. The suckers on the tentacles, and the arms, are not known to be any bigger than about five to five and a half centimeters. The carpal region has a dense cluster of suckers, in six to seven irregular, transverse rows.

The Architeuthidae also have fins that are proportionally small, ovoid, and without free anterior lobes. The fins at the rear of the mantle, are used to help the squid move by gentle, rhythmic pulses of water pushed out of the mantle cavity throughout the funnel.

They also have eight arms with suckers in two longitudinal rows. At the end of the arms they have a parrot-like beaks at the base. Another characteristic of the squid is that they have buccal connectives that attach to the dorsal borders of arms.

Giant squid contain the dark, sepia-colored ink that we associate with the smaller, more familiar squid.

They have the two, very large gills resting inside the mantle cavity. The squid are able to breath and move quickly by expanding the mantle cavity by contracting sets of muscles within the mantle. The water fills the expanded space, the muscles relax, and the elastic mantle then snaps back to a smaller size, jetting water out through the funnel. The jet of water closes the flaps on either side of the squid's head so water can exit only through the funnel.

The nervous system of the squids are very extensive and they even also have a complex brain. For this reason they are under extensive research. The circulatory system is closed which is a distinct characteristic of the squid.(Portner, et al 1994) (Forch 1998)

Reproduction

The reproduction of Architeuthis is not well known. Hypotheses are based on observations of the sexual characteristics in dead Architeuthis and from the knowledge of other squid

Females produce enormous quantities of whitish to cream-colored eggs, about .5-1.4 mm long and .3-.7 mm wide, depending on the stage of their maturity. One female had over 5000 gm(over 11 pounds) of eggs in her ovary, well in excess of a million eggs. As in most oegopsids, females have a single median ovary in the posterior end of the mantle cavity, paired, convoluted oviducts along with mature eggs pass, then exit through the oviducal glands, and large nidamental glands that produce quantities of gelatinous material. Whether the eggs are laid into a large gelatinous matrix, as in most of the large oceanic squids or are released individually, is unknown, although the large nidamental glands suggest the former method.

Males tend to reach sexual maturity at a smaller size than do females. The two ventral arms are reported to be modified into transfering the spermatophores to the female. As in most other cephalopods, the single, posterior testis produces sperm that move into a complex system of glands that manufacture the spermatophores. These are stored in the elongate sac, or Needham's sac from which they are expelled during mating. The Needham's sac of fully mature males is packed with hundreds of spermatophores. Needham's sac terminates in the penis. The penis is so elongate that it extends anteriorly beyond the mantle opening. While mating has not been observed and the exact role of the penis is uncertain, some females have been found with spermatangia, the sperm-containing sacs of the spermatophore, embedded in the tissue around the bases of the arms and the head.

Cephalopods are known to be very fast growing animals. Some species of small, shallow water forms reach sexual maturity in 6-8 months, and most species about which growth, age and maturity data are available reach reproductive capacity within 12-18 months. Many of the specimens of Architeuthis that have been recovered have been mature, especially the females. But the age at maturity of Architeuthis is not known with certanity. One study suggests that adult size is attained within 3 years. Even at the rapid growth rate expected in cephalopods, the attainment of a mass of 500 kg or more in fewer than 3 years is impressive.

(Nesis 1987)

Behavior

Since scientists have never observed giant squid alive in their natural habitat, they cannot say what its behavior is like. There is no way to know for sure how Architeuthis individuals interact with each other. One thing that scientist have hypothesized is that Architeuthis may be solitary hunters. They believe this because no two Architeuthis have ever been caught in fishing nets together. (Forch 1998)

Food Habits

For many years, nobody knew what the giant squid utilized for food. This is because they have never really been observed in the wild. Some recent studies on dead individuals have shown that giant squid eat deep-sea fishes, such as orange ruffie, and hokie. They also eat other types of deep-sea squids, but not Architeuthis, the giant squid.

As large as these animals are, they would probably be able to capture almost anything, maybe even whales(see comments)! They capture their prey by using their two long feeding tentacles. The tentacles are shot out to grip the prey. The suckers on the tips of tentacles grab hold of the prey and the tentacles contract, bringing the prey to the arms. The arms then further subdue the prey, pulling it to the strong, sharp beaks. The beaks are operated by a massive set of muscles that allow them to bite through just about anything the squid might capture. But the giant squid's bite-sized pieces of food need further shredding before being digested. The tongue is equipped with an organ known as the radula, which is loaded with rows of small, file-like teeth. The radula further shreds the meal before the tongue pushes it down the esophagus to the digestive organs.

There are very few predators of the adult giant squid. The best and probably only one is the sperm whale. As babies and juveniles, they have many pedators, mostly deep sea fishes. Once giant squid get beyond a certain size, they have outgrown the size of most of their potential predators. Sperm whales grow to 40-50 feet in length, but they weigh 30-40 tons. So even though a giant squid is huge, it is not big enough to escape or to fight with a sperm whale. Most of the time the sperm whale wins. This is evident in the number of giant squid found in the stomach of the sperm whale. (Forch 1998) (Banister and Campbell 1985)

Economic Importance for Humans: Positive

Since not much is known, it is hard to tell how important it is to humans. It could be an essential part of the food chain, and if it is disrupted it could hurt the whales, for which we do have uses. The squid and other cephalopods have a very distinct and elaborate nervous system and brain. The giant squid could help us understand and learn more about nervous systems, maybe even ours. (Nesis 1987, Gilbert, et al 1990)

Economic Importance for Humans: Negative

As of right now, there really are no adverse effects on humans. We just recently found out it existed! The only minor problem it presents is that it can get entangled in fishing nets, but that itself is not a serious problem. (Nesis 1987)

Conservation Status

The number of individuals of this species is unknown.(Forch 1998)

Other Comments

Since few of these species have been seen alive, there are many stories, myths, and mysteries about the giant squid, and often these are associated with danger. The giant squid has even been called a sea monster. New technology will likely enable us to not only look for and hopefully find the giant squid, as well as explore and discover in the deep-sea habitat.

Contributors

Jerrod Vaughan (author), Southwestern University, Stephanie Fabritius (editor), Southwestern University.

Glossary

Arctic Ocean

the body of water between Europe, Asia, and North America which occurs mostly north of the Arctic circle.

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Pacific Ocean

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.

benthic

Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.

bilateral symmetry

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.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

native range

the area in which the animal is naturally found, the region in which it is endemic.

References

Banister, K., A. Campbell. 1985. The Encyclopedia of Aquatic Life. New York, NY: Facts on File.

Forch, E. 1998. The Marine Fauna of New Zealand: Cephalopoda: Oegopsida: Architeuthidae (Giant Squid). Wellington: National Institute of Water and Atmospheric Research.

Gilbert, D., W. Adelman, J. Arnold. 1990. Squid as Experimental Animals. New York, NY: Plenum Press.

Nesis, K. 1987. Cephalopods of the World: Squids, Cuttlefishes, Octopuses and Allies. Neptune, N.J.: T.F.H Publications.

Portner, H., R. O'Dor, D. Macmillan. 1994. Physiology of Cephalopod Molluscs. Switzerland: Gordon and Breach Publishers.