The Mustelidae (; from Latin , weasel) are a diverse family of carnivoran mammals, including weasels,

badger Badgers are medium-sized short-legged omnivores in the superfamily Musteloidea. Badgers are a polyphyletic rather than a natural taxonomic grouping, being united by their squat bodies and adaptions for fossorial activity rather than by the ...

otter Otters are carnivorous mammals in the subfamily Lutrinae. The 13 extant otter species are all semiaquatic, aquatic, or marine. Lutrinae is a branch of the Mustelidae family, which includes weasels, badgers, mink, and wolverines, among ...

s, polecats, martens, grisons, and

wolverine The wolverine ( , ; ''Gulo gulo''), also called the carcajou or quickhatch (from East Cree, ''kwiihkwahaacheew''), is the largest land-dwelling species, member of the family Mustelidae. It is a muscular carnivore and a solitary animal. The w ...

s. Otherwise known as mustelids (), they form the largest family in the suborder

Caniformia Caniformia is a suborder within the order Carnivora consisting of "dog-like" carnivorans. They include Canidae, dogs (Wolf, wolves, foxes, etc.), bears, raccoons, and Mustelidae, mustelids. The Pinnipedia (pinniped, seals, walruses and sea lions) ...

of the order

Carnivora Carnivora ( ) is an order of placental mammals specialized primarily in eating flesh, whose members are formally referred to as carnivorans. The order Carnivora is the sixth largest order of mammals, comprising at least 279 species. Carnivor ...

with about 66 to 70 species in nine subfamilies.

Variety

Mustelids vary greatly in size and behaviour. The smaller variants of the least weasel can be under in length, while the giant otter of Amazonian South America can measure up to and sea otters can exceed in weight.

Wolverine The wolverine ( , ; ''Gulo gulo''), also called the carcajou or quickhatch (from East Cree, ''kwiihkwahaacheew''), is the largest land-dwelling species, member of the family Mustelidae. It is a muscular carnivore and a solitary animal. The w ...

s can crush bones as thick as the femur of a

moose The moose (: 'moose'; used in North America) or elk (: 'elk' or 'elks'; used in Eurasia) (''Alces alces'') is the world's tallest, largest and heaviest extant species of deer and the only species in the genus ''Alces''. It is also the tal ...

to get at the marrow, and have been seen attempting to drive

bear Bears are carnivoran mammals of the family (biology), family Ursidae (). They are classified as caniforms, or doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats ...

s away from their kills. The sea otter uses rocks to break open shellfish to eat. Martens are largely

arboreal Arboreal locomotion is the locomotion of animals in trees. In habitats in which trees are present, animals have evolved to move in them. Some animals may scale trees only occasionally (scansorial), but others are exclusively arboreal. The hab ...

, while European badgers dig extensive tunnel networks, called setts. Only one mustelid has been domesticated; the ferret. Tayra are also kept as pets (although they require a Dangerous Wild Animals licence in the UK), or as working animals for hunting or vermin control. Others have been important in the

fur trade The fur trade is a worldwide industry dealing in the acquisition and sale of animal fur. Since the establishment of a world fur market in the early modern period, furs of boreal ecosystem, boreal, polar and cold temperate mammalian animals h ...

—the mink is often raised for its fur. Being one of the most species-rich families in the order Carnivora, the family Mustelidae also is one of the oldest. Mustelid-like forms first appeared about 40 million years ago (Mya), roughly coinciding with the appearance of

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

s. The common ancestor of modern mustelids appeared about 18 Mya.

Characteristics

Within a large range of variation, the mustelids exhibit some common characteristics. They are typically small animals with elongated bodies, short legs, short skulls, short, round ears, and thick fur. Mustelids' long, slender body structure is adapted to three main lifestyles: terrestrial, arboreal, and aquatic/semi-aquatic. They exhibit digitigrade or plantigrade locomotion, with five toes on each foot, enabling them to move in different ways (i.e. digging, climbing, swimming). Most mustelids are solitary, nocturnal animals, and are active year-round. Their dense fur, often serving as natural camouflage, undergoes seasonal changes to help them adjust to varying environmental conditions. With the exception of the sea otter they have anal scent glands that produce a strong-smelling secretion the animals use for sexual signalling and marking territory. Mustelids exhibit sexual dimorphism, with males being larger than females, but degree varies between species as well as geographically within species. Male mustelids have a bifurcated penis and baculum. Most mustelid reproduction involves

embryonic diapause Embryonic diapause (delayed implantation in mammals) is a reproductive strategy used by a number of animal species across different biological classes. In more than 130 types of mammals where this takes place, the process occurs at the blastocys ...

. The

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

does not immediately implant in the

uterus The uterus (from Latin ''uterus'', : uteri or uteruses) or womb () is the hollow organ, organ in the reproductive system of most female mammals, including humans, that accommodates the embryonic development, embryonic and prenatal development, f ...

, but remains dormant for some time. No development takes place as long as the embryo remains unattached to the uterine lining. As a result, the normal gestation period is extended, sometimes up to a year. This allows the young to be born under favourable environmental conditions. Reproduction has a large energy cost, so it is to a female's benefit to have available food and mild weather. The young are more likely to survive if birth occurs after previous offspring have been weaned. Mustelids are predominantly carnivorous, although some eat vegetable matter at times. While not all mustelids share an identical

dentition Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiology ...

, they all possess teeth adapted for eating flesh, including the presence of shearing

carnassial Carnassials are paired upper and lower teeth modified in such a way as to allow enlarged and often self-sharpening edges to pass by each other in a shearing manner. This adaptation is found in carnivorans, where the carnassials are the modified f ...

s. One characteristic trait is a meat-shearing upper-back molar that is rotated 90°, towards the inside of the mouth. With variation between species, the most common dental formula is .

Ecology

The fisher, tayra, and martens are partially arboreal, while badgers are

fossorial A fossorial animal () is one that is adapted to digging and which lives primarily (but not solely) underground. Examples of fossorial vertebrates are Mole (animal), moles, badgers, naked mole-rats, meerkats, armadillos, wombats, and mole salamand ...

. A number of mustelids have aquatic lifestyles, ranging from

semiaquatic In biology, being semi-aquatic refers to various macroorganisms that live regularly in both aquatic and terrestrial environments. When referring to animals, the term describes those that actively spend part of their daily time in water (in ...

minks and river otters to the fully aquatic sea otter, which is one of the few nonprimate mammals known to use tools while foraging. It uses "anvil" stones to crack open the shellfish that form a significant part of its diet. It is a " keystone species", keeping its prey populations in balance so some do not outcompete the others and destroy the kelp in which they live. The black-footed ferret is entirely dependent on another keystone species, the prairie dog. A family of four ferrets eats 250 prairie dogs in a year; this requires a stable population of prairie dogs from an area of some .

Animals of similar appearance

Skunks were previously included as a subfamily of the mustelids, but DNA research placed them in their own separate family (Mephitidae). Mongooses bear a striking resemblance to many mustelids, but belong to a distinctly different suborder—the

Feliformia Feliformia is a suborder within the order Carnivora consisting of "cat-like" carnivorans, including Felidae, cats (large and small), hyenas, mongooses, viverrids, and related taxa. Feliformia stands in contrast to the other suborder of Carnivora, ...

(all those carnivores sharing more recent origins with the

cats The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the ...

) and not the

(those sharing more recent origins with the dogs). Because mongooses and mustelids occupy similar

ecological niche In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources an ...

convergent evolution Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last comm ...

has led to similarity in form and behavior.

Human uses

Several mustelids, including the mink, the sable (a type of marten), and the stoat (ermine), possess

furs A fur is a soft, thick growth of hair that covers the skin of almost all mammals. It consists of a combination of oily guard hair on top and thick underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as an ...

that are considered beautiful and valuable, so have been hunted since prehistoric times. From the early Middle Ages, the trade in furs was of great economic importance for northern and eastern European nations with large native populations of fur-bearing mustelids, and was a major economic impetus behind Russian expansion into

Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...

and French and English expansion in North America. In recent centuries fur farming, notably of mink, has also become widespread and provides the majority of the fur brought to market. One species, the sea mink (''Neogale macrodon'') of New England and Canada, was driven to

extinction Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

by fur trappers. Its appearance and habits are almost unknown today because no complete specimens can be found and no systematic contemporary studies were conducted. The sea otter, which has the densest fur of any animal, narrowly escaped the fate of the sea mink. The discovery of large populations in the North Pacific was the major economic driving force behind Russian expansion into

Kamchatka The Kamchatka Peninsula (, ) is a peninsula in the Russian Far East, with an area of about . The Pacific Ocean and the Sea of Okhotsk make up the peninsula's eastern and western coastlines, respectively. Immediately offshore along the Pacific ...

, the

Aleutian Islands The Aleutian Islands ( ; ; , "land of the Aleuts"; possibly from the Chukchi language, Chukchi ''aliat'', or "island")—also called the Aleut Islands, Aleutic Islands, or, before Alaska Purchase, 1867, the Catherine Archipelago—are a chain ...

, and

Alaska Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...

, as well as a cause for conflict with

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

and foreign hunters in the Kuril Islands. Together with widespread hunting in California and British Columbia, the species was brought to the brink of extinction until an international moratorium came into effect in 1911. Today, some mustelids are threatened for other reasons. Sea otters are vulnerable to

oil spill An oil spill is the release of a liquid petroleum hydrocarbon into the environment, especially the marine ecosystem, due to human activity, and is a form of pollution. The term is usually given to marine oil spills, where oil is released into th ...

s and the indirect effects of overfishing; the black-footed ferret, a relative of the European polecat, suffers from the loss of American

prairie Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the ...

; and

populations are slowly declining because of

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

and persecution. The rare European mink (''Mustela lutreola'') is one of the most

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

mustelid species. The ferret, a domesticated European polecat, is a fairly common pet.

Evolution and systematics

Mustelidae is a subfamily in Musteloidia, a superfamily of mammals that is united by shared skull and teeth characteristics. Mustelids are believed to have separated from their next closest related family, Procyonidae, around 29 million years ago. The oldest known mustelid from North America is '' Corumictis wolsani'' from the early and late Oligocene (early and late Arikareean, Ar1–Ar3) of

Oregon Oregon ( , ) is a U.S. state, state in the Pacific Northwest region of the United States. It is a part of the Western U.S., with the Columbia River delineating much of Oregon's northern boundary with Washington (state), Washington, while t ...

. Middle Oligocene ''Mustelictis'' from Europe might be a mustelid, as well. Other early fossils of the mustelids were dated at the end of the Oligocene to the beginning of the Miocene. Which of these forms are Mustelidae ancestors and which should be considered the first mustelids is unclear. The fossil record indicates that mustelids appeared in the late Oligocene period (33 Mya) in Eurasia and migrated to every continent except Antarctica and Australia (all the continents that were connected during or since the early Miocene). They reached the Americas via the Bering land bridge. The 68 recent mustelids (66 extant species) are classified into eight subfamilies in 22 genera: Subfamily Taxidiinae * Genus '' Taxidea'' ** American badger, ''T. taxus'' Subfamily Mellivorinae * Genus '' Mellivora'' ** Honey badger, ''M. capensis'' Subfamily Melinae * Genus '' Arctonyx'' ** Northern hog badger, ''A. albogularis'' ** Greater hog badger, ''A. collaris'' ** Sumatran hog badger, ''A. hoevenii'' * Genus '' Meles'' ** Japanese badger, ''M. anakuma'' ** Asian badger, ''M. leucurus'' ** European badger, ''M. meles'' ** Caucasian badger, ''M. canescens'' Subfamily Helictidinae * Genus '' Melogale'' ** Vietnam ferret-badger, ''M. cucphuongensis'' ** Bornean ferret-badger, ''M. everetti'' ** Chinese ferret-badger, ''M. moschata'' ** Javan ferret-badger, ''M. orientalis'' ** Burmese ferret-badger, ''M. personata'' ** Formosan ferret-badger, ''M. subaurantiaca'' Subfamily Guloninae * Genus '' Eira'' ** Tayra, ''E. barbara'' * Genus '' Gulo'' **

, ''G. gulo'' * Genus '' Martes'' ** American marten, ''M. americana'' ** Pacific marten, ''M. caurina'' ** Yellow-throated marten, ''M. flavigula'' ** Beech marten, ''M. foina'' ** Nilgiri marten, ''M. gwatkinsii'' ** European pine marten, ''M. martes'' ** Japanese marten, ''M. melampus'' ** Sable, ''M. zibellina'' * Genus '' Pekania'' ** Fisher, ''P. pennanti'' Subfamily

Ictonychinae Ictonychinae is a subfamily of the mammal Family (biology), family Mustelidae found mainly in the Neotropics (three species) and Africa (three species), with one Eurasian member. It includes the grisons, Patagonian weasel, Ictonyx, striped poleca ...

* Genus '' Galictis'' ** Lesser grison, ''G. cuja'' ** Greater grison, ''G. vittata'' * Genus '' Ictonyx'' ** Saharan striped polecat, ''I. libycus'' ** Striped polecat, ''I. striatus'' * Genus '' Lyncodon'' ** Patagonian weasel, ''L. patagonicus'' * Genus '' Poecilogale'' **

African striped weasel The African striped weasel (''Poecilogale albinucha''), also known as the white-naped weasel, striped weasel or African weasel, is a small mammal native to sub-Saharan Africa, where its range stretches from as far north as Kenya down south to So ...

, ''P. albinucha'' * Genus '' Vormela'' ** Marbled polecat, ''V. peregusna'' Subfamily Lutrinae (

s) * Genus '' Aonyx'' ** African clawless otter, ''A. capensis'' ** Asian small-clawed otter, ''A. cinerea'' ** Congo clawless otter, ''A. congicus'' * Genus '' Enhydra'' ** Sea otter, ''E. lutris'' * Genus '' Lontra'' **

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 endemism, lives only on the North American continent throughout most of Canada, along the coasts of the U ...

, ''L. canadensis'' ** Marine otter, ''L. felina'' ** Neotropical otter, ''L. longicaudis'' ** Southern river otter, ''L. provocax'' * Genus '' Lutra'' **

Eurasian otter The Eurasian otter (''Lutra lutra''), also known as the European otter, Eurasian river otter, European river otter, common otter, and Old World otter, is a semiaquatic mammal native to Eurasia and the Maghreb. The most widely distributed member o ...

, ''L. lutra'' ** Hairy-nosed otter, ''L. sumatrana'' ** Japanese otter. ''L. nippon'' * Genus '' Hydrictis'' ** Spotted-necked otter, ''H. maculicollis'' * Genus '' Lutrogale'' ** Smooth-coated otter, ''L. perspicillata'' * Genus ''

Pteronura The giant otter or giant river otter (''Pteronura brasiliensis'') is a South American carnivorous mammal. It is the longest member of the weasel family, Mustelidae, a globally successful group of predators, reaching up to . Atypical of musteli ...

'' ** Giant otter, ''P. brasiliensis'' Subfamily

Mustelinae Mustelinae is a subfamily of Family (biology), family Mustelidae, including weasels, ferrets, and minks. __TOC__ It was formerly defined in a paraphyletic manner to also include wolverines, martens, and many other mustelids, to the exclusion of ...

(weasels, ferrets, and mink) * Genus '' Mustela'' ** Mountain weasel, ''M. altaica'' ** Stoat (Beringian ermine), ''M. erminea'' ** Steppe polecat, ''M. eversmannii'' ** Domestic ferret, ''M. furo'' ** Haida ermine, ''M. haidarum'' ** Japanese weasel, ''M. itatsi'' ** Yellow-bellied weasel, ''M. kathiah'' ** European mink, ''M. lutreola'' ** Indonesian mountain weasel, ''M. lutreolina'' ** Black-footed ferret, ''M. nigripes'' ** Least weasel, ''M. nivalis'' ** Malayan weasel, ''M. nudipes'' ** European polecat, ''M. putorius'' ** American ermine, ''M. richardsonii'' **

Siberian weasel The Siberian weasel or kolonok (''Mustela sibirica'') is a medium-sized weasel native to Asia, where it is widely distributed and inhabits various forest habitats and open areas. It is therefore listed as Least Concern on the IUCN Red List. Descr ...

, ''M. sibirica'' ** Back-striped weasel, ''M. strigidorsa'' * Genus ''

Neogale ''Neogale'' (colloquially referred to as the New World weasels) is a genus of Carnivora, carnivorous, highly active small Mammal, mammals belonging to the Mustelidae family (which also contains badgers, weasels, martens, otters, and wolverines, ...

'' ** Amazon weasel, ''N. africana'' ** Colombian weasel, ''N. felipei'' ** Long-tailed weasel, ''N. frenata'' ** American mink, ''N. vison'' ** Sea mink, ''N. macrodon'' Fossil mustelids Extinct genera of the family Mustelidae include: * '' Brachypsalis'' * '' Chamitataxus'' * '' Corumictis'' * '' Cyrnaonyx'' * '' Ekorus'' * ''

Enhydriodon ''Enhydriodon'' is an extinct genus of otters known from Africa, Pakistan, and India that lived from the late Miocene to the early Pleistocene. It contains nine confirmed species, two debated species, and at least a few other undescribed species ...

'' * '' Eomellivora'' * ''Hoplictis'' * '' Megalictis'' * '' Oligobunis'' * '' Plesictis'' * '' Sthenictis'' * '' Teruelictis'' * ''Trochictis''

Phylogeny

Multigene phylogenies constructed by Koepfli et al. (2008) and Law et al. (2018) found that Mustelidae comprises eight living subfamilies. The early mustelids appear to have undergone two rapid bursts of diversification in Eurasia, with the resulting species spreading to other continents only later. File:MustelidaePhylogeneticTree (edited).jpg, Phylogenetic tree of Mustelidae. Contains 53 of the 79 putative mustelid species. File:Mustelidae timetree (edited).jpg, Time-calibrated tree of Mustelidae showing divergence times between lineages. Split times include: 28.8 million years ( Ma) for mustelids vs. procyonids; 17.8 Ma for Taxidiinae; 15.5 Ma for Mellivorinae; 14.8 Ma for Melinae; 14.0 Ma for Guloninae + Helictidinae; 11.5 Ma for Guloninae + Naquinae vs. Helictidinae; 12.0 Ma for Ictonychinae; 11.6 Ma for Lutrinae vs. Mustelinae. Mustelid species diversity is often attributed to an adaptive radiation coinciding with the mid-Miocene climate transition. Contrary to expectations, Law et al. (2018) found no evidence for rapid bursts of lineage diversification at the origin of the Mustelidae, and further analyses of lineage diversification rates using molecular and fossil-based methods did not find associations between rates of lineage diversification and mid-Miocene climate transition as previously hypothesized.

References

External links

The Mighty Weasel
(February 19, 2020) – ''

Nature Nature is an inherent character or constitution, particularly of the Ecosphere (planetary), ecosphere or the universe as a whole. In this general sense nature refers to the Scientific law, laws, elements and phenomenon, phenomena of the physic ...

'' {{Authority control Carnivorans Mammal families Extant Oligocene first appearances Taxa named by Gotthelf Fischer von Waldheim