Eurasian otter

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Eurasian otter
Fischotter, Lutra Lutra.JPG
Scientific classification Red Pencil Icon.png
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Mustelidae
Subfamily: Lutrinae
Genus: Lutra
Species:
L. lutra
Binomial name
Lutra lutra
European Otter area.png
Range map
Synonyms

Mustela lutraLinnaeus, 1758
Lutra vulgaris Erxleben, 1777

Contents

The Eurasian otter (Lutra lutra), also known as the European otter, Eurasian river otter, common otter, and Old World otter, is a semiaquatic mammal native to Eurasia. The most widely distributed member of the otter subfamily (Lutrinae) of the weasel family (Mustelidae), it is found in the waterways and coasts of Europe, many parts of Asia, and parts of northern Africa. The Eurasian otter has a diet mainly of fish, and is strongly territorial. It is endangered in some parts of its range, but is recovering in others.

Description

The Eurasian otter is a typical species of the otter subfamily. Brown above and cream below, these long, slender creatures are well-equipped for their aquatic habits. Their bones show osteosclerosis, increasing their density to reduce buoyancy. [2] This otter differs from the North American river otter by its shorter neck, broader visage, the greater space between the ears and its longer tail. [3] However, the Eurasian otter is the only otter in much of its range, so it is rarely confused for any other animal. Normally, this species is 57 to 95 cm (22.5 to 37.5 in) long, not counting a tail of 35–45 cm (14–17.5 in). The female is shorter than the male. [4] The otter's average body weight is 7 to 12 kg (15 to 26 lb), although occasionally a large old male may reach up to 17 kg (37 lb). [5] [6] The record-sized specimen, reported by a reliable source but not verified, weighed over 24 kg (53 lb). [7]

Distribution and habitat

Two otters in Korkeasaari Zoo, Helsinki, Finland Saukko Korkeasaari 2.jpg
Two otters in Korkeasaari Zoo, Helsinki, Finland

The Eurasian otter is the most widely distributed otter species, its range including parts of Asia and Africa, as well as being spread across Europe, south to Palestine. Though currently believed to be extinct in Liechtenstein and Switzerland, they are now very common in Latvia, along the coast of Norway, in the western regions of Spain and Portugal and across Great Britain, especially Shetland, where 12% of the UK breeding population exists. [8] Ireland's otters are geographically widespread and believed to be the most stable population in Europe. [9] In Italy, they can be found in southern parts of the peninsula. The South Korean population is endangered. In India, the species is distributed in the Himalayan foothills, southern Western Ghats and the central Indian landscape. [10]

In general, their varied and adaptable diets mean they may inhabit any unpolluted body of fresh water, including lakes, streams, rivers, canals and ponds, as long as the food supply is adequate. In Andalusia, the golf courses became part of their habitat. [11] Eurasian otters may also live along the coast, in salt water, but require regular access to fresh water to clean their fur. When living in the sea, individuals of this species are sometimes referred to as "sea otters", but they should not be confused with the true sea otter, a North Pacific species much more strongly adapted to a marine existence.

The extinct Japanese otter is sometimes considered a subspecies; recent studies have found it to fall outside the subspecific clades comprising L. lutra, so it has been reclassified as a distinct species, but significant uncertainty remains. [12]

Behaviour and ecology

Diet

Otter feeding on fish European Otter.jpg
Otter feeding on fish
Video of otters eating frozen fish in the Aquarium of Gijón, Spain

The Eurasian otter's diet mainly consists of fish. [13] Fish is its most preferred choice of food in Mediterranean and temperate freshwater habitats. [14] During the winter and in colder environments, it also feeds on amphibians, [15] [16] crustaceans, insects, birds and sometimes small mammals, including young European beavers. [17]

Breeding

Skull of a Eurasian otter Lutra lutra 04 MWNH 414.jpg
Skull of a Eurasian otter

Eurasian otters are strongly territorial, living alone for the most part. An individual's territory may vary between about 1 and 40 km (1–25 mi) long, with about 18 km (11 mi) being usual. The length of the territory depends on the density of food available and the width of the water suitable for hunting (it is shorter on coasts, where the available width is much wider, and longer on narrower rivers). The Eurasian otter uses its feces, called spraints, to mark its territory and prioritize the use of resources to other group members. [18] The territories are only held against members of the same sex, so those of males and females may overlap. [19] Mating takes place in water. Eurasian otters are nonseasonal breeders (males and females will breed at any time of the year) and it has been found that their mating season is most likely determined simply by the otters' reproductive maturity and physiological state. Female otters become sexually mature between 18 and 24 months old and the average age of first breeding is found to be 2+12 years. Gestation for the Eurasian otter is 60–64 days, the litter weighing about 10% of the female body mass. After the gestation period, one to four pups are born, which remain dependent on the mother for about 13 months. [20] The male plays no direct role in parental care, although the territory of a female with her pups is usually entirely within that of the male. [19] Hunting mainly takes place at night, while the day is usually spent in the Eurasian otter's holt (den) – usually a burrow or hollow tree on the riverbank which can sometimes only be entered from underwater. Though long thought to hunt using sight and touch only, evidence is emerging that they may also be able to smell underwater – possibly in a similar manner to the star-nosed mole. [21] [22]

Conservation

A Eurasian otter skeleton Otterbones.jpg
A Eurasian otter skeleton

The Eurasian otter declined across its range in the second half of the 20th century [23] primarily due to pollution from pesticides such as organochlorine and polychlorinated biphenyls. Other threats included habitat loss and hunting, both legal and illegal. [24] Eurasian otter populations are now recovering in many parts of Europe. In the United Kingdom, the number of sites with an otter presence increased by 55% between 1994 and 2002. [25] In August, 2011, the Environment Agency announced that otters had returned to every county in England since vanishing from every county except the West Country and parts of Northern England. [26] Recovery is partly due to a ban on the most harmful pesticides that has been in place across Europe since 1979, [27] partly to improvements in water quality leading to increases in prey populations, and partly to direct legal protection under the European Union Habitats Directive [28] and national legislation in several European countries. [29] [30] [31] In Hong Kong, it is a protected species under Wild Animals Protection Ordinance Cap 170. It is listed as Near Threatened by the IUCN Red List. [1]

It is listed as endangered in Pakistan, India, Bangladesh, Myanmar and Thailand, and critically endangered in Mongolia. [1] In South Korea, it is listed as a Natural Monument [32] and first-class endangered species. [33]

Most species that are victims of population decline or a loss of habitat tend to eventually lose their genetic difference due to inbreeding from small populations. A study conducted in 2001, examined whether or not the populations of Eurasian otters suffered from a lack of genetic variability. In the study, they examined teeth of otter skulls at the Zoological Museum, Copenhagen and the Natural History Museum, Aarhus. The samples were collected between 1883 and 1963 in Denmark (Funen, Zealand, and Jutland). The study examined the tissue on the teeth of the skulls and determined the genetic variability based on DNA analysis. In conclusion, the study discovered that despite the population declines, the Eurasian otter was not a victim of declining genetic variability. [34]

The decline in population of native freshwater fishes in the rivers of Iberia, which is the preferred food of Eurasian otters, along with the expansion of exotic fish species like centrarchids could potentially put Eurasian otters at risk for extinction. [35]

Related Research Articles

Hellbender Species of amphibian

The hellbender, also known as the hellbender salamander, is a species of aquatic giant salamander endemic to the eastern and central United States. A member of the family Cryptobranchidae, the hellbender is the only extant member of the genus Cryptobranchus. Other closely related salamanders in the same family are in the genus Andrias, which contains the Japanese and Chinese giant salamanders. The hellbender, which is much larger than all other salamanders in its geographic range, employs an unusual means of respiration, and fills a particular niche—both as a predator and prey—in its ecosystem, which either it or its ancestors have occupied for around 65 million years. The species is listed as Near Threatened on the IUCN Red List of Threatened Species.

Otter Subfamily of mammals (Lutrinae)

Otters are carnivorous mammals in the subfamily Lutrinae. The 13 extant otter species are all semiaquatic, aquatic or marine, with diets based on fish and invertebrates. Lutrinae is a branch of the Mustelidae family, which also includes weasels, badgers, mink, and wolverines, among other animals.

Eurasian beaver Species of beaver

The Eurasian beaver or European beaver is a beaver species that was once widespread in Eurasia, but was hunted to near-extinction for both its fur and castoreum. At the turn of the 20th century, only about 1,200 beavers survived in eight relict populations in Europe and Asia. It has been reintroduced to much of its former range, and now occurs from Spain, Central Europe, Great Britain and Scandinavia to a few regions in China and Mongolia. It is listed as least concern on the IUCN Red List, as it recovered well in most of Europe. It is extinct in Portugal, Moldova, and Turkey.

Asian small-clawed otter Species of mammal

The Asian small-clawed otter, also known as the oriental small-clawed otter and the small-clawed otter, is an otter species native to South and Southeast Asia. It has short claws that do not extend beyond the pads of its webbed digits. With a total body length of 730 to 960 mm, it is the smallest otter species in the world.

Sacramento perch Species of fish

The Sacramento perch is an endangered sunfish native to the Sacramento–San Joaquin River Delta, Pajaro, and Salinas River areas in California, but widely introduced throughout the western United States.

Redbreast sunfish Species of fish

The redbreast sunfish is a species of freshwater fish in the sunfish family of order Perciformes. The type species of its genus, it is native to the river systems of eastern Canada and the United States. The redbreast sunfish reaches a maximum recorded length of about 30 centimetres (12 in).

North American river otter Species of semi-aquatic mammal

The North American river otter, also known as the northern river otter or common otter, is a semiaquatic mammal endemic to the North American continent found in and along its waterways and coasts. An adult North American river otter can weigh between 5.0 and 14 kg. The river otter is protected and insulated by a thick, water-repellent coat of fur.

<i>Lutra</i> Genus of carnivores

Lutra is a genus of otters, one of seven in the subfamily Lutrinae.

Neotropical otter A species of mammals belonging to the weasel, badger, otter, marten, mink, and wolverine family of carnivores

The neotropical otter or neotropical river otter is an otter species found in Middle America, South America, and the island of Trinidad. It is physically similar to the northern and southern river otter, which occur directly north and south of this species' range. The length of the neotropical otter can range from 36–66 centimetres (14–26 in), plus a tail of 37–84 centimetres (15–33 in). Body weight ranges from 5–15 kilograms (11–33 lb). Otters are members of the family Mustelidae, the most species-rich family in the order Carnivora.

European perch Species of fish

The European perch, also known as the common perch, redfin perch, big-scaled redfin, English perch, Eurasian perch, Eurasian river perch, Hatch or in Anglophone parts of Europe, simply the perch, is a predatory species of the freshwater perch native to Europe and northern Asia. The species is a popular quarry for anglers, and has been widely introduced beyond its native area, into Australia, New Zealand, and South Africa. They have caused substantial damage to native fish populations in Australia and have been proclaimed a noxious species in New South Wales.

Hairy-nosed otter Species of carnivore

The hairy-nosed otter is a semiaquatic mammal endemic to Southeast Asia and one of the rarest and least known otter species. It is threatened by loss of natural resources and poaching.

Southern river otter Species of semi-aquatic mammal

The southern river otter is a species of otter that lives in Chile and Argentina. Although called a "river otter", it inhabits both marine and freshwater environments. It sometimes is considered a subspecies of Lontra canadensis. The southern river otter is listed as endangered, due to illegal hunting, water pollution, and habitat loss.

Spotted-necked otter Species of carnivore

The spotted-necked otter, or speckle-throated otter, is an otter native to sub-Saharan Africa.

Smooth-coated otter Species of carnivore

The smooth-coated otter is an otter species occurring in most of the Indian subcontinent and Southeast Asia, with a disjunct population in Iraq. It is listed as Vulnerable on the IUCN Red List since 1996 and is threatened by habitat loss, pollution of wetlands and poaching for the illegal wildlife trade. As its name indicates, its fur is smooth and shorter than that of other otter species.

Japanese otter Species of otter

The Japanese otter (Japanese: ニホンカワウソ or Japanese river otter is an extinct species of otter formerly widespread in Japan.

Spotted sunfish Species of fish

The spotted sunfish is a member of the freshwater sunfish family Centrarchidae and order perciformes. The redspotted sunfish, redear sunfish and pumpkinseed sunfish are its closest relatives. Lepomis punctatus is olive-green to brown in color with black to reddish spots at the base of each scale that form rows of dots on the side. The scientific name punctatus refers to this spotted pattern. It was first described in 1831 by Valenciennes.

<i>Potamon ibericum</i> Species of crab

Potamon ibericum is a Eurasian species of freshwater crab. It is an omnivore that feeds on land, but returns regularly to the water, and can survive short periods of drought in burrows and under stones. Its natural range stretches from north-eastern Greece, around both sides of the Black Sea and to beyond the Caspian Sea; populations have also been introduced to southern France. It is included as a near threatened species on the IUCN Red List, and is included in the Red Data Book for Ukraine. It belongs to the genus Potamon.

Biodiversity of Albania

For a small country, Albania is characterised by a considerable wealth of terrestrial and marine ecosystems and habitats with contrasting floral and faunal species, defined in an area of 28,748 square kilometres. Most of the country is predominantly of Mediterranean character, comprehending the country's center and south, while the alpine affinity is more visible in the northeast.

References

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Further reading