Squid facts for kids
Quick facts for kids Squid |
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| Bigfin reef squid, Sepioteuthis lessoniana | |
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Teuthida
A. Naef, 1916
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Squid are cephalopods of the order Teuthida. They are the sister group to the octopods. Squid are carnivores and, in turn, they are hunted. The largest squid, the giant squid and colossal squid, are eaten by sperm whales and sleeper sharks.
There are about 300 species of squid.
Contents
Characteristics
Squid, like cuttlefish, have eight arms arranged in pairs, and two longer tentacles with suckers.
All squid have a mouth with a radula, and jet propulsion with the siphon from the mantle. The radulla is a scraping organ in the mouth that scrapes nutrients from food sources.
Tentacles are used for locomotive power and capturing food sources. All squids are carnivores; they eat other animals, not plants.
Like other cephalopoda, squid are intelligent animals. Squids have a head-like structure, with sense organs and brains in the front end. Although the squids lack exterior shells they have a vestigial shell inside, made of chitin.
The skin is covered in chromatophores, which enable the squid to change colour to suit its surroundings, making it effectively camouflaged. Controlled by the nervous system, the camouflage can change in 'real time'.
Squid reproduction
After a male and female mate, the female squid lays eggs. The eggs are laid inside an egg case. Since the squid is usually a part of a shoal, it is laid with many other egg cases from many other squids, and then anchored to the sea floor. Because of this, squid eggs are often (many times) found in clumps, and those clumps often look like a flower.
Often, the male will die a short time after mating, and the female will die once she has released her eggs. Because of this, squids usually lay eggs only once. Squids do not live very long. Although there are some long-lived species, most squids live for only one or two years.
Size
Most squid are no more than 60 centimetres (24 in) long, although the giant squid may reach 13 metres (43 ft).
In 1978, sharp, curved claws on the suction cups of squid tentacles cut up the rubber coating on the hull of the USS Stein. The size suggested the largest squid known at the time.
In February 2007, a New Zealand fishing vessel caught a colossal squid weighing 495 kilograms (1,091 lb) and measuring around 10 metres (33 ft) off the coast of Antarctica. This specimen is the largest invertebrate ever found. Squid have the largest eyes in the animal kingdom.
Giant squid are featured in literature and folklore with a frightening connotation. The Kraken is a legendary tentacled monster possibly based on sightings of real giant squid.
Human uses
In literature and art
Giant squid have featured as monsters of the deep since classical times. Giant squid were described by Aristotle (4th century BC) in his History of Animals and Pliny the Elder (1st century AD) in his Natural History. The Gorgon of Greek mythology may have been inspired by squid or octopus, the animal itself representing the severed head of Medusa, the beak as the protruding tongue and fangs, and its tentacles as the snakes. The six-headed sea monster of the Odyssey, Scylla, may have had a similar origin. The Nordic legend of the kraken may also have derived from sightings of large cephalopods.
In literature, H. G. Wells' short story "The Sea Raiders" featured a man-eating squid species Haploteuthis ferox. The science fiction writer Jules Verne told a tale of a kraken-like monster in his 1870 novel Twenty Thousand Leagues Under the Sea.
As food
Squid form a major food resource and are used in cuisines around the world, notably in Japan where it is eaten as ika sōmen, sliced into vermicelli-like strips; as sashimi; and as tempura. Three species of Loligo are used in large quantities, L. vulgaris in the Mediterranean (known as Calamar in Spanish, Calamaro in Italian); L. forbesii in the Northeast Atlantic; and L. pealei on the American East Coast. Among the Ommastrephidae, Todarodes pacificus is the main commercial species, harvested in large quantities across the North Pacific in Canada, Japan and China.
In English-speaking countries, squid as food is often called calamari, adopted from Italian into English in the 17th century. Squid are found abundantly in certain areas, and provide large catches for fisheries. The body can be stuffed whole, cut into flat pieces, or sliced into rings. The arms, tentacles, and ink are also edible; the only parts not eaten are the beak and gladius (pen). Squid is a good food source for zinc and manganese, and high in copper, selenium, vitamin B12, and riboflavin.
Commercial fishing
According to the FAO, the cephalopod catch for 2002 was 3,173,272 tonnes (6.995867×109 lb). Of this, 2,189,206 tonnes, or 75.8 percent, was squid.
Images for kids
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Basic squid features (ventral aspect)
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Fossil Loligosepia aalensis from the lower Jurassic; the ink sac is still full of black eumelanin pigment
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Hectocotylus of Uroteuthis duvauceli: one tentacle of the male is adapted for transferring the spermatophore
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Ventral view of the viscera of a female Chtenopteryx sicula
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The body of glass squids (Cranchiidae) is mainly filled by a transparent coelom containing ammonium ions for buoyancy.
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A giant squid. The bars are a metre (3 feet) apart.
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Hawaiian bobtail squid swimming slowly by undulating its fins
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The whip-like tentacles of Mastigoteuthis are covered with tiny suckers to catch small organisms like flypaper
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The Caribbean reef squid (Sepioteuthis sepioidea) employs a complex array of colour changes during courtship and social interactions
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Squid eggs
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Fossil Rhomboteuthis from the Lower Callovian (c. 164 mya, middle Jurassic) of La Voulte-sur-Rhône, France
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Fossil Plesioteuthis from the Tithonian (c. 150 mya, upper Jurassic), Solnhofen, Germany
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Controllable chromatophores of different colours in the skin of a squid allow it to change its coloration and patterns rapidly, whether for camouflage or signalling.
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Principle of counter-illumination camouflage of the firefly squid, Watasenia scintillans. When seen from below by a predator, the animal's light helps to match its brightness and colour to the sea surface above.
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See also
In Spanish: Calamar para niños
