Definitions

otter

otter

[ot-er]
otter, name for a number of aquatic, carnivorous mammals of the weasel family, found on all continents except Australia. The common river otters of Eurasia and the Americas are species of the genus Lutra. The North American river otter, L. canadensis, ranges from N Alaska and Canada to the S United States. Its slender body is 21/2 to 3 ft (76-91 cm) long, excluding the 12-in. (30-cm), heavy tail; it weighs from 10 to 25 lb (4-10 kg). It has thick, glossy brown fur, which is commercially valuable. The head is flattened, the legs are short, and the hind feet are webbed. An agile swimmer, it fishes in streams and lakes, along the banks of which it makes its burrow. It also eats frogs, crayfish, and other water animals. Although it spends most of its time in water, it makes overland trips on occasion. The otter is a social and playful animal; groups have been seen playing "follow the leader," sliding down mudbanks, or tobogganing in the snow, apparently for the sake of pleasure. Of the freshwater otters, the South American giant otter, Pteronura brasiliensis, is the most highly modified for aquatic life. Its highly streamlined body is up to 7 ft (213 cm) long, the tail is keeled, and the feet are short, webbed, and nearly useless on land. Its mouth is set under the muzzle, like that of a shark. Hunted extensively for its fur, the giant otter may be in danger of extinction over much of its range. Otters of other genera are found in Africa and SE Asia. The sea otter, Enhydra lutris, found in and around the kelp beds of the N Pacific, is the only exclusively marine species, although river otters sometimes enter the ocean at the mouths of rivers. The sea otter swims on its back and in this position carries its cub and eats its meals of abalone, crab, and sea urchin, sometimes using a rock to smash open the shells. Relentless hunting of the animal led to its near extinction; however, it is now protected by international agreement. Otters are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Carnivora, family Mustelidae.

See E. Park, The World of the Otter (1972); P. Chanin, The Natural History of Otters (1985).

Otter, Peaks of, two peaks, W central Va., in the Blue Ridge, W of Lynchburg. The one, Flat Top, is 4,004 ft (1,220 m) high; the other, Sharp Top, 3,875 ft (1,181 m). They are on national parkland administered as part of the Blue Ridge National Parkway.

River otter (Lutra canadensis).

Any of 13 species of semiaquatic, web-footed carnivores in the weasel family (Mustelidae), found throughout Africa, North and South America, Europe, and Asia. Otters have the same general proportions as weasels. Size varies among species, but total length is typically 3–7 ft (1–2 m), and weight is 6.5–60 lb (3–26 kg); the large sea otter is an exception. Otter fur—e.g., that of North American river otters—is highly valued. Most species live near rivers, some live near lakes or streams, and the sea otter is completely marine. Otters eat small aquatic animals. They are inquisitive and playful; a favourite sport is sliding down mud or snow banks.

Learn more about otter with a free trial on Britannica.com.

(born Oct. 22, 1821, Harwinton, Conn., U.S.—died Aug. 13, 1900, Raquette Lake, N.Y.) U.S. railroad magnate. He worked as a peddler before becoming a prosperous merchant in Oneonta, N.Y. In the gold rush year of 1849, he moved to Sacramento, Calif., and joined Mark Hopkins in a firm that specialized in miners' supplies. In the late 1850s he became interested in a plan to link California with the eastern U.S. by rail. In 1861 he joined Hopkins, Leland Stanford, and Charles Crocker (1822–1888)—a group later known as the “Big Four”—to form the Central Pacific Railroad. During its construction (1863–69), Huntington lobbied for the company in the east, securing financing and favourable legislation from the federal government. In 1865 the Big Four formed the Southern Pacific Railroad. In 1869 Huntington bought the Chesapeake and Ohio Railway, which he later extended to link with the Southern Pacific, forming the first transcontinental railroad. He became president of the Southern Pacific–Central Pacific system in 1890.

Learn more about Huntington, Collis P(otter) with a free trial on Britannica.com.

Otters are semi- aquatic (or in one case aquatic) fish-eating mammals. The otter subfamily Lutrinae forms part of the family Mustelidae, which also includes weasels, polecats, badgers, as well as others. With thirteen species in seven genera, otters have an almost worldwide distribution. They mainly eat aquatic animals, predominantly fish and shellfish, but also other invertebrates, amphibians, birds and small mammals.

Etymology and terminology

The word otter derives from the Old English word otr, otor or oter. This and cognate words in other Indo-European languages ultimately stem from a root which also gave rise to the English words water, wet and winter.

An otter's den is called a holt. Male otters are dog-otters, females are bitches and babies are cubs or pups. The collective noun for otters is pack or sometimes romp, being descriptive of their often playful nature.

Characteristics

Otters have long, slim bodies and relatively short limbs, with webbed paws. Most have sharp claws on their feet, and all except the sea otter have long muscular tails.

They have a very soft underfur which is protected by their outer layer of long guard hair. This traps a layer of air, and keeps them dry and warm under water.

Diet and Behavior

Otters do not depend on their specialized fur alone for survival in the cold waters where many live: they also have very high metabolic rates. For example Eurasian otters must eat 15% of their body-weight a day, and sea otters 20 to 25%, depending on the temperature. In water as warm as 10°C (50°F) an otter needs to catch 100 grams (3 oz) of fish per hour to survive. Most species hunt for 3 to 5 hours a day, and nursing mothers up to 8 hours a day.

Most otters have fish as the primary item in their diet, supplemented by frogs, crayfish and crabs. Some are expert at opening shellfish, and others will take any available small mammals or birds. This prey-dependence leaves otters very vulnerable to prey depletion.

Otters are very active, chasing prey in the water or searching the beds of rivers, lakes or the sea. Most species live beside water, entering it mainly to hunt or travel, otherwise spending much of their time on land to avoid their fur becoming waterlogged. The sea otter does live in the sea for most of its life.

Otters are playful animals, for example sliding repeatedly down snowy slopes, apparently from sheer enjoyment. Different species vary in their social structure, with some being largely solitary, while others live in groups – in a few species these groups may be fairly large.

Species

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Cladogram, after Koepfli et al 2008 and Bininda-Emonds et al 1999

Genus Lutra

Genus Hydrictis

Genus Lutrogale

Genus Lontra

Genus Pteronura

Genus Aonyx

Genus Enhydra

Northern river otter

The northern river otter (Lontra canadensis) became one of the major animals hunted and trapped for fur in North America after European contact. River otters eat a variety of fish and shellfish, as well as small land mammals and birds. They grow to one metre (3 to 4 ft) in length and weigh from five to fifteen kilograms (10 to 30 lb).

In some areas this is a protected species, and some places have otter sanctuaries, which help ill and injured otters to recover.

Sea otter

Sea otters (Enhydra lutris) live along the Pacific coast of North America. Their historic range included shallow waters of the Bering Strait and Kamchatka, and as far south as Japan. Sea otters have some 200 thousand strands of hair per square centimetre of skin, a rich fur for which humans hunted them almost to extinction. By the time the 1911 Fur Seal Treaty gave them protection, so few sea otters remained that the fur trade had become unprofitable.

Sea otters eat shellfish and other invertebrates (especially clams, abalone, and sea urchins ), frequently using rocks as crude tools to smash open shells. They grow to 1.0 to 1.5 metres (2.5 to 5 ft) in length and weigh 30 kilograms (65 lb). Although once near extinction, they have begun to spread again, from remnant populations in California and Alaska.

Unlike most marine mammals (such as seals or whales), sea otters do not have a layer of insulating blubber. As with other species of otter, they rely on a layer of air trapped in their fur, which they keep topped up by blowing into the fur from their mouths. They spend most of their time in the water, whereas other otters spend much of their time on land.

Eurasian otter

This species (Lutra lutra) inhabits Europe, and its range also extends across most of Asia and parts of North Africa. In the British Isles they occurred commonly as recently as the 1950s, but became rare in many areas due to the use of chlorinated hydrocarbon pesticides and as a result of habitat-loss and water pollution (they remained relatively common in parts of Scotland and Ireland). Population levels attained a low point in the 1980s, but are now recovering strongly. The UK Biodiversity Action Plan envisages the re-establishment of otters by 2010 in all the UK rivers and coastal areas that they inhabited in 1960. Roadkill deaths have become one of the significant threats to the success of their re-establishment.

Giant otter

The giant otter (Pteronura brasiliensis) inhabits South America, especially the Amazon river basin, but is becoming increasingly rare due to poaching, habitat loss, and the use of mercury and other toxins in illegal alluvial gold mining. This gregarious animal grows to a length of up to 1.8 metres (6 ft), and is more aquatic than most other otters.

Cultural references

Norse mythology tells of the dwarf Ótr habitually taking the form of an otter. The myth of Otter's Ransom is the starting point of the Volsunga saga.

In some Native American cultures, otters are considered totem animals.

The otter is held to be a clean animal belonging to Ahura Mazda in Zoroastrian belief, and taboo to kill.

Gallery

References and further reading

  • Gallant, D., L. Vasseur, & C.H. Bérubé (2007). Unveiling the limitations of scat surveys to monitor social species: a case study on river otters. Journal of Wildlife Management 71:258–265.

External links

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