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
Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelag ...
. 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
Osteosclerosis is a disorder that is characterized by abnormal hardening of bone and an elevation in bone density. It may predominantly affect the medullary portion and/or cortex of bone. Plain radiographs are a valuable tool for detecting and ...
, increasing their density to reduce buoyancy. This otter differs from the
North American river otter
The North American river otter (''Lontra canadensis''), also known as the northern river otter and river otter, is a semiaquatic mammal that only lives on the North American continent, along its waterways and coasts. An adult North American ri ...
by its shorter neck, broader visage, the greater space between the ears and its longer tail. 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 long, not counting a tail of . The female is shorter than the male. The otter's average body weight is , although occasionally a large old male may reach up to . The record-sized specimen, reported by a reliable source but not verified, weighed over .
Distribution and habitat
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 thought to be extinct in
Liechtenstein
Liechtenstein (), officially the Principality of Liechtenstein (german: link=no, Fürstentum Liechtenstein), is a German language, German-speaking microstate located in the Alps between Austria and Switzerland. Liechtenstein is a semi-constit ...
and
Switzerland, it is now common in
Latvia
Latvia ( or ; lv, Latvija ; ltg, Latveja; liv, Leţmō), officially the Republic of Latvia ( lv, Latvijas Republika, links=no, ltg, Latvejas Republika, links=no, liv, Leţmō Vabāmō, links=no), is a country in the Baltic region of ...
, along the coast of
Norway
Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...
, in the western regions of
Spain
, image_flag = Bandera de España.svg
, image_coat = Escudo de España (mazonado).svg
, national_motto = '' Plus ultra'' ( Latin)(English: "Further Beyond")
, national_anthem = (English: "Royal March")
, ...
and
Portugal
Portugal, officially the Portuguese Republic, In recognized minority languages of Portugal:
:* mwl, República Pertuesa is a country located on the Iberian Peninsula, in Southwestern Europe, and whose territory also includes the Macaronesian ...
and across
Great Britain
Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is ...
and
Ireland
Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...
. In
Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical ...
, it lives in southern parts of the peninsula.
[
It inhabits unpolluted bodies of fresh water such as lakes, streams, rivers, canals and ponds, as long as the food supply is adequate. In ]Andalusia
Andalusia (, ; es, Andalucía ) is the southernmost autonomous community in Peninsular Spain. It is the most populous and the second-largest autonomous community in the country. It is officially recognised as a "historical nationality". The ...
, it uses artificial lakes on golf courses. It prefers the open areas of the streams and also lives along the coast in salt water, but requires regular access to fresh water to clean its fur.
In Syria, the Eurasian otter was recorded in montane creeks in Latakia
, coordinates =
, elevation_footnotes =
, elevation_m = 11
, elevation_ft =
, postal_code_type =
, postal_code =
, area_code = Country code: 963 City code: 41
, geocode ...
and Raqqa Governorate
Raqqa Governorate ( ar, مُحافظة الرقة, Muḥāfaẓat ar-Raqqah) is one of the fourteen governorates of Syria. It is situated in the north of the country and covers an area of 19,618 km2. The capital is Raqqa. The Islamic Stat ...
s and in the lower Euphrates valley in Deir ez-Zor Governorate
Deir ez-Zor Governorate ( ar, مُحافظة دير الزور / ALA-LC: ''Muḥāfaẓat Dayr az-Zawr'') is one of the fourteen governorates (provinces) of Syria. It is situated in eastern Syria, bordering Iraq. It has an area of 33,060 km2 ...
.
In western Nepal
Nepal (; ne, नेपाल ), formerly the Federal Democratic Republic of Nepal ( ne,
सङ्घीय लोकतान्त्रिक गणतन्त्र नेपाल ), is a landlocked country in South Asia. It is ma ...
, its presence was documented at elevations of around in Barekot river in Jajarkot District and at in Tubang river in Eastern Rukum District
Eastern Rukum ( ne, पूर्वी रुकुम) is a mountain district of Lumbini Province of Nepal situated along the Dhaulagiri mountain range. It is also the only mountain district of the province with its tallest mountain Putha Hi ...
.
In India
India, officially the Republic of India ( Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the ...
, it is distributed in the Himalaya
The Himalayas, or Himalaya (; ; ), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau. The range has some of the planet's highest peaks, including the very highest, Mount Everest. Over 10 ...
n foothills, southern Western Ghats and the central Indian landscape.
Behaviour and ecology
Diet
The Eurasian otter's diet mainly consists of fish. Fish is its most preferred choice of food in Mediterranean and temperate freshwater habitats. During the winter and in colder environments, it also feeds on amphibians, crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...
s, insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...
s, bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s and sometimes small mammals, including young European beavers.
As with various other mustelid species, otters are capable of overpowering and killing prey significantly larger than themselves, and are known to hunt large waterbirds such as adult greylag geese on occasion.
Breeding
Eurasian otters are strongly territorial, living alone for the most part. An individual's territory may vary between about long, with about 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. The territories are only held against members of the same sex, so those of males and females may overlap. Mating
In biology, mating is the pairing of either opposite- sex or hermaphroditic organisms for the purposes of sexual reproduction. ''Fertilization'' is the fusion of two gametes. '' Copulation'' is the union of the sex organs of two sexually rep ...
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
Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemica ...
state. Female otters become sexually mature between 18 and 24 months old and the average age of first breeding is found to be years. Gestation
Gestation is the period of development during the carrying of an embryo, and later fetus, inside viviparous animals (the embryo develops within the parent). It is typical for mammals, but also occurs for some non-mammals. Mammals during preg ...
for the Eurasian otter is 60–64 days, the litter
Litter consists of waste products that have been discarded incorrectly, without consent, at an unsuitable location. Litter can also be used as a verb; to litter means to drop and leave objects, often man-made, such as aluminum cans, paper cups ...
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. 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. 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.
Taxonomy
The extinct Japanese otter
The (''Lutra nippon'') or Japanese river otter is an extinct species of otter formerly widespread in Japan.
Dating back to the 1880s, it was even seen in Tokyo. The population suddenly shrank in the 1930s, and the mammal nearly vanished. Sinc ...
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.
Conservation
The Eurasian otter declined across its range in the second half of the 20th century primarily due to pollution from pesticides
Pesticides are substances that are meant to pest control, control pest (organism), pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microb ...
such as organochlorine and polychlorinated biphenyl
Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act in 1979 and internationally by ...
s. Other threats included habitat loss
Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
and hunting, both legal and illegal. Eurasian otter populations are now recovering in many parts of Europe. In the United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...
, the number of sites with an otter presence increased by 55% between 1994 and 2002. In August, 2011, the Environment Agency
The Environment Agency (EA) is a non-departmental public body, established in 1996 and sponsored by the United Kingdom government's Department for Environment, Food and Rural Affairs, with responsibilities relating to the protection and en ...
announced that otters had returned to every county in England since vanishing from every county except the West Country and parts of Northern England. Recovery is partly due to a ban on the most harmful pesticides that has been in place across Europe since 1979, partly to improvements in water quality leading to increases in prey populations, and partly to direct legal protection under the European Union Habitats Directive
The Habitats Directive (more formally known as Council Directive 92/43/EEC on the Conservation of natural habitats and of wild fauna and flora) is a directive adopted by the European Community in 1992 as a response to the Berne Convention. The ...
and national legislation in several European countries. In Hong Kong
Hong Kong ( (US) or (UK); , ), officially the Hong Kong Special Administrative Region of the People's Republic of China (abbr. Hong Kong SAR or HKSAR), is a city and special administrative region of China on the eastern Pearl River Delta i ...
, it is a protected species under Wild Animals Protection Ordinance Cap 170. It is listed as Near Threatened
A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify fo ...
by the IUCN Red List
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
.
It is listed as endangered in Pakistan, India, Bangladesh
Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the List of countries and dependencies by population, eighth-most populous country in the world, with a population exceeding 165 million pe ...
, Myanmar
Myanmar, ; UK pronunciations: US pronunciations incl. . Note: Wikipedia's IPA conventions require indicating /r/ even in British English although only some British English speakers pronounce r at the end of syllables. As John Wells explai ...
and Thailand, and critically endangered in Mongolia
Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 millio ...
. In South Korea
South Korea, officially the Republic of Korea (ROK), is a country in East Asia, constituting the southern part of the Korea, Korean Peninsula and sharing a Korean Demilitarized Zone, land border with North Korea. Its western border is formed ...
, it is listed as a Natural Monument and first-class endangered species.
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 Natural History Museum (Danish: Naturhistorisk Museum) in Aarhus is a Danish museum specializing in natural history.
The Natural History Museum is an independent institution financed with contributions from the Ministry of Culture, Aarhus ...
. The samples were collected between 1883 and 1963 in Denmark (Funen
Funen ( da, Fyn, ), with an area of , is the third-largest island of Denmark, after Zealand and Vendsyssel-Thy. It is the 165th-largest island in the world. It is located in the central part of the country and has a population of 469,947 as o ...
, Zealand
Zealand ( da, Sjælland ) at 7,031 km2 is the largest and most populous island in Denmark proper (thus excluding Greenland and Disko Island, which are larger in size). Zealand had a population of 2,319,705 on 1 January 2020.
It is th ...
, and Jutland
Jutland ( da, Jylland ; german: Jütland ; ang, Ēota land ), known anciently as the Cimbric or Cimbrian Peninsula ( la, Cimbricus Chersonesus; da, den Kimbriske Halvø, links=no or ; german: Kimbrische Halbinsel, links=no), is a peninsula of ...
). 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.
The decline in population of native freshwater fishes in the rivers of Iberia
The Iberian Peninsula (),
**
* Aragonese and Occitan: ''Peninsula Iberica''
**
**
* french: Péninsule Ibérique
* mwl, Península Eibérica
* eu, Iberiar penintsula also known as Iberia, is a peninsula
A peninsula (; ) is a la ...
, 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.[Blanco-Garrido, F., Prenda, J., Narvaez, M. “Eurasian otter (Lutra lutra) diet and prey selection in Mediterranean streams invaded by centrarchid fishes.” Springer Science+Business Media B.V., 2007.]
References
Further reading
* Laidler, Liz. ''Otters in Britain''. David & Charles, 1982.
External links
{{DEFAULTSORT:otter, Eurasian
Eurasian otter
Carnivorans of Asia
Carnivorans of Europe
Endangered animals
Endangered biota of Asia
Endangered biota of Europe
Near threatened animals
Eurasian otter
Eurasian otter
Articles containing video clips
Semiaquatic mammals