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80-510: The Mustelidae ( / m ʌ ˈ s t ɛ l ɪ d iː / ; from Latin mustela , weasel) are a diverse family of carnivoran mammals, including weasels , badgers , otters , polecats , martens , grisons , and wolverines . Otherwise known as mustelids ( / ˈ m ʌ s t ɪ l ɪ d z / ), they form the largest family in the suborder Caniformia of the order Carnivora with about 66 to 70 species in nine subfamilies. Mustelids vary greatly in size and behaviour. The smaller variants of

160-581: A septum . Caniforms have single-chambered or partially divided auditory bullae, composed of a single bone. Initially, the early representatives of carnivorans were small as the creodonts (specifically, the oxyaenids) and mesonychians dominated the apex predator niches during the Eocene, but in the Oligocene, carnivorans became a dominant group of apex predators with the nimravids , and by the Miocene most of

240-440: A correlation between habitat and color pattern; for example spotted or banded species tend to be found in heavily forested environments. Some species like the grey wolf are polymorphic with different individual having different coat colors. The arctic fox ( Vulpes lagopus ) and the stoat ( Mustela erminea ) have fur that changes from white and dense in the winter to brown and sparse in the summer. In pinnipeds and polar bears ,

320-802: A diet of aquatic invertebrates which is crucial to the otter's survival in the water. Sea otters also belong to the family Mustelidae . When compared with other mustelids, such as the river otter , weasels , and minks , the sea otter shows distinct hindlimb anatomy which could contribute to propulsion and stability at the surface of the water while the forelimbs manipulate tools and food. E. lutris has significantly larger gluteus muscles than other mustelids. Sea otter forelimbs are small and not used in swimming. Forelimb structure, particularly musculature and skeletal anatomy, are potentially adapted for, "tactile sensitivity and tool use associated with detection, handling, and consumption of prey". The lower incisors of sea otters protrude and are shaped like spades,

400-473: A dive and immediately lie on the surface of the water with their chests up and place a stone on the chest to function as an anvil. The average length of a dive is 55 seconds. Otters hold mussels so as to orient the flat sides of the mussels against the "palms" of the paws and the seam of the two shells contacts the stone in a pounding instance. Mussels are pounded against rock or stones at a rate of two pounds per second. It takes approximately 35 blows to crack open

480-410: A genetic component to stone behaviours in otters – as this would explain both its occurrence without models and its cross-occurrence across species that do not observe each other. Otters that use stones to open prey do not use stones every time they need to manipulate their prey. Crabs , for example, can be ripped apart by the forelimbs and then eaten. Otters will store a stone in the pouch of skin under

560-670: A hammer, separately, but used on the same prey item at once. Tool reuse is demonstrated by the use of the same stone in a variety of feeding opportunities over one large feeding period. There have also been observed instances of tool use methods which do not involve stone or kelp, but rather parts of the prey itself. These have been specifically seen as otters taking pieces of shell or crab carapace. Otters will take advantage of nearby objects, occasionally using, "empty shells, driftwood, empty glass, or other discarded man made objects. Live clams are also pounded against each other". Sea otters most commonly use stones as anvils. They do not express

640-454: A mussel. In order to extract abalones from their substrate, otters demonstrate a hammering method by picking up rocks from the bottom of the ocean and hammering the abalone free from the substrate. Once on the surface, the otter may use the anvil method to continue to crack the abalone shell. Otters may also use a stone to hammer a prey item that is rested on the chest. Otters commonly wrap crabs in strands of kelp to immobilize them and leave

720-462: A preference for the shape of the stone or rock, but they do choose fairly large stones, between 6 and 15 cm (2.4 and 5.9 in), to rest on their chests. While all sub-species of otters use the forelimbs to rip open urchins, the Californian otters were observed to have used rocks as a surface to pound urchins and crabs, as well as mussels (observed most frequently). Otters seem to rise from

800-451: A random and curious manner. According to some of the earlier otter behavior biologists, Hall and Schaller, this, "tendency to manipulate and pound is far from stereotyped in its application and seems to prove the basis for learning the use of tools in feeding behavior". The first indications of tool use are observed at 5 weeks of age when pups will slap their forepaws against their chest. By ten weeks of age, they attempt consecutive dives with

880-513: A shape which may facilitate their ability to scoop food out of shellfish . During consumption of sea urchins, otters use a tool or their paws to crack open the sea urchins and scoop out the gonads and viscera with the lower incisors (12). The canines are blunt, and the post-canines are bunodont. Their flat and broad shape is useful for chewing a combination of soft invertebrates and the harder parts of tougher invertebrates, like shell fragments and sea urchin tests. Sea otters also have some of

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960-473: A significant difference between the occurrence of tool use in Amchitka Island, Alaska and Monterey, California . Alaskan otters used tools on 1% of dives, while Californian otters used tools on 16% of dives. All otter pups generally use tools if their mothers did. However, females are more likely to use tools to crush their prey in situations where the prey does not necessarily require a stone. It

1040-473: A supporting amount of evidence that Miacoidea is an evolutionary grade of carnivoramorphs that, while viverravids are monophyletic basal group, the miacids are paraphyletic in respect to Carnivora (as shown in the phylogeny below). Carnivoramorpha as a whole first appeared in the Paleocene of North America about 60 million years ago. Crown carnivorans first appeared around 42 million years ago in

1120-442: A thick insulating layer of blubber helps maintain their body temperature. Carnivorans are arguably the group of mammals of most interest to humans. The dog is noteworthy for not only being the first species of carnivoran to be domesticated , but also the first species of any taxon. In the last 10,000 to 12,000 years, humans have selectively bred dogs for a variety of different tasks and today there are well over 400 breeds. The cat

1200-646: A wide array of body plans, varying greatly in size and shape. Carnivora are divided into two suborders , the Feliformia , containing the true felids and several " cat -like" animals; and the Caniformia , containing the true canids and many " dog -like" animals. The feliforms include the Felidae , Viverridae , hyena , and mongoose families, the majority of which live only in the Old World; cats are

1280-514: Is Corumictis wolsani from the early and late Oligocene (early and late Arikareean , Ar1–Ar3) of Oregon . 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

1360-682: Is a table chart of the extant carnivoran families and number of extant species recognized by various authors of the first (2009 ) and fourth (2014 ) volumes of the Handbook of the Mammals of the World : The canine teeth are usually large, conical, thick and stress resistant. All of the terrestrial species of carnivorans have three incisors on each side of each jaw (the exception is the sea otter ( Enhydra lutris ) which only has two lower incisor teeth). The third molar has been lost. The carnassial pair

1440-486: Is an order of placental mammals that have specialized in primarily 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 on every major landmass and in a variety of habitats, ranging from the cold polar regions of Earth to the hyper-arid region of the Sahara Desert and the open seas. Carnivorans exhibit

1520-475: Is another domesticated carnivoran and it is today considered one of the most successful species on the planet, due to their close proximity to humans and the popularity of cats as pets. Many other species are popular, and they are often charismatic megafauna . Many civilizations have incorporated a species of carnivoran into their culture: a prominent example is the lion , viewed as a symbol of power and royalty in many societies. Yet many species such as wolves and

1600-428: Is made up of the fourth upper premolar and the first lower molar teeth. Like most mammals, the dentition is heterodont , though in some species, such as the aardwolf ( Proteles cristata ), the teeth have been greatly reduced and the cheek teeth are specialised for eating insects. In pinnipeds, the teeth are homodont as they have evolved to grasp or catch fish, and the cheek teeth are often lost. In bears and raccoons,

1680-830: Is observed with regards to the Northern Pacific and the Southern Pacific. In Point Lobos, the use of tools to open mussels is very common. This behavior is distinctly less common in northern areas like the Commander Islands and Kuril Islands . There, adult otters only use tools if they are unable to open food items after trying first with their teeth. Alaskan otters do not use tools as often as Californian otters. Californian otters show multiple techniques with differences that are tailored specifically to eating bivalves and crabs. A study that compiled seventeen years' worth of observational data demonstrated

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1760-428: Is potential evidence of vertical social transmission. Overall, stone behavior likely also has a genetic component - this follows from the development of this behaviour in the absence of models, and from the fact that stone behavior occurs across a wide range of otter species. Mother otters appear to make sacrifices in order to help their pups. In Prince William Sound it was observed that, "the diet of females with pups

1840-400: Is suspected that matrilineal transmission can explain the observed female sex bias. Female otters also display more variation in the types of tool-use methods they employ. During long-term studies to record behavior, it is frequently recorded that some, individual otters do not use tools at all. Instead, these otters target soft-bodied prey like fish, or urchins which can be ripped apart with

1920-492: The Aleutian Islands , less tool use is recorded and sea otters consume much more fish. The diet in these areas also includes sea urchins, which otters can break with their forepaws, mollusks , and crustaceans . Sea otters demonstrate at least three distinct methods of tool use. Two pertain to the use of stones and one pertains to the use of kelp as an anchor. Stones can be used as anvils, in which they are rested on

2000-494: The Caribbean monk seal ( Neomonachus tropicalis ) in 1952. Some species such as the red fox ( Vulpes vulpes ) and stoat ( Mustela erminea ) have been introduced to Australasia and have caused many native species to become endangered or even extinct. Tool use by sea otters It is not possible to pin-point when sea otters began using tools consistently. It is hypothesized that certain behaviors were selected for, in

2080-477: The Cretaceous–Paleogene extinction event . These early ancestors of carnivorans would have resembled small weasel or genet -like mammals, occupying a nocturnal shift on the forest floor or in the trees, as other groups of mammals like the mesonychians and later the creodonts were occupying the megafaunal faunivorous niche. However, following the extinction of mesonychians and the oxyaenid creodonts at

2160-558: The Middle Eocene . Their molecular phylogeny shows the extant Carnivora are a monophyletic group, the crown group of the Carnivoramorpha . From there carnivorans have split into two clades based on the composition of the bony structures that surround the middle ear of the skull, the cat-like feliforms and the dog-like caniforms . In feliforms, the auditory bullae are double-chambered, composed of two bones joined by

2240-487: The big cats have been broadly hunted, resulting in extirpation in some areas. Habitat loss and human encroachment as well as climate change have been the primary cause of many species going into decline. Four species of carnivorans have gone extinct since the 1600s: Falkland Island wolf ( Dusicyon australis ) in 1876; the sea mink ( Neogale macrodon ) in 1894; the Japanese sea lion ( Zalophus japonicus ) in 1951 and

2320-433: The cats ) and not the Caniformia (those sharing more recent origins with the dogs ). Because mongooses and mustelids occupy similar ecological niches , convergent evolution has led to similarity in form and behavior. Several mustelids, including the mink, the sable (a type of marten), and the stoat (ermine), possess furs that are considered beautiful and valuable, so have been hunted since prehistoric times. From

2400-519: 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 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

2480-432: 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,

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2560-596: The least weasel can be under 20 cm (8 in) in length, while the giant otter of Amazonian South America can measure up to 1.7 m (5 ft 7 in) and sea otters can exceed 45 kg (99 lb) in weight. Wolverines can crush bones as thick as the femur of a moose to get at the marrow , and have been seen attempting to drive bears away from their kills. The sea otter uses rocks to break open shellfish to eat. Martens are largely arboreal , while European badgers dig extensive tunnel networks, called setts . Only one mustelid has been domesticated;

2640-554: 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. Carnivora Carnivora ( / k ɑːr ˈ n ɪ v ər ə / kar- NIH -vər-ə )

2720-492: 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 500 acres (2.0 km). 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 (all those carnivores sharing more recent origins with

2800-539: The Aleutian Islands, it was discovered that anywhere from 10% to 93% of individuals in a population use tools. Some otters have developed very specific, individual behaviors that do not necessarily demonstrate tool use, but do demonstrate dexterity. Individuals in California have learned how to tear open aluminum cans that float in the water from incidents of pollution. Small octopuses commonly reside in

2880-633: The North Pacific was the major economic driving force behind Russian expansion into Kamchatka , the Aleutian Islands , and Alaska , as well as a cause for conflict with Japan 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 spills and

2960-399: The appearance of rodents . The common ancestor of modern mustelids appeared about 18 Mya. 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. Most mustelids are solitary, nocturnal animals, and are active year-round. With the exception of

3040-529: The arm to eat prey with both forelimbs, such as crabs, and then retrieve the stone at a later instance. Otters have been observed to use a clam shell as a digging tool and as a pry tool as well. This seems to imply, "an anticipation of use that goes beyond the immediate situation". If a stone appears to be particularly good for opening one food item, it will be kept for several others. In an observation of an otter in Point Lobos State Park , it

3120-470: The arms. A sea otter may capture more than two different food items on a single dive. In all populations of sea otters, soft-bodied organisms such as worms and sea stars are the least likely to be consumed with the aid of tools. On the other hand, shelled bivalves and snails with shells are the most likely to be cracked open with tools. Otters of the Northern Pacific consume mostly sea urchins and fish, thereby exhibiting less tool use behavior. Otters of

3200-485: The behavior and therefore learned to repeat the behavior consistently. Sea otters commonly exhibit swimming behavior where they swim on their backs. The features which facilitate swimming on the back also facilitate tool use. Otters that do not use tools still feed on their backs. This habit of feeding on the surface with the chest up facilitates a flat surface for resting rocks and pounding items together (1). Once discovered and consistently performed by one or some otters,

3280-453: The cans and the sea otters attempt to eat the small octopuses. Others have learned to reach on the stern of small boats to obtain bait fish or squid . Otters are not immune to paralytic shellfish poisoning , despite some popular belief that they are. However, they have the ability to manipulate their prey enough to avoid the paralytic shellfish poisoning toxins so that they do not consume lethal amounts. Alaskan sea otters prey heavily on

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3360-406: The carnassial pair is secondarily reduced. The skulls are heavily built with a strong zygomatic arch . Often a sagittal crest is present, sometimes more evident in sexually dimorphic species such as sea lions and fur seals , though it has also been greatly reduced in some small carnivorans. The braincase is enlarged with the frontoparietal bone at the front. In most species, the eyes are at

3440-421: The chest of an otter lying on the ocean surface. Hard prey items can be pounded against the anvil to create cracks and facilitate access to flesh. Stones can also be used as hammers, primarily to extract shellfish from their substrates. Other important aspects of otter tool-use behaviors include the use of tool composites and tool reuse. Tool composite is the term given to the combination of two rocks as an anvil and

3520-403: The clade Ferae . Ferae includes the closest extant relative of carnivorans, the pangolins , as well as several extinct groups of mostly Paleogene carnivorous placentals such as the creodonts , the arctocyonians , and mesonychians . The creodonts were originally thought of as the sister taxon to the carnivorans, perhaps even ancestral to, based on the presence of the carnassial teeth , but

3600-443: The dental and cranial features, not much of their overall anatomy unites carnivorans as a group. All species of carnivorans are quadrupedal and most have five digits on the front feet and four digits on the back feet. In terrestrial carnivorans, the feet have soft pads. The feet can either be digitigrade as seen in cats, hyenas and dogs or plantigrade as seen in bears, skunks, raccoons, weasels, civets and mongooses. In pinnipeds,

3680-468: 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 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

3760-482: The end of the Eocene, carnivorans quickly moved into this niche, with forms like the nimravids being the dominant large-bodied ambush predators during the Oligocene alongside the hyaenodont creodonts (which similarly produced larger, more open-country forms at the start of the Oligocene). By the time Miocene epoch appeared, most if not all of the major lineages and families of carnivorans had diversified and become

3840-759: The extant carnivoran families have diversified and become the primary terrestrial predators in the Northern Hemisphere. In 1758, the Swedish botanist Carl Linnaeus placed all carnivorans known at the time into the group Ferae (not to be confused with the modern concept of Ferae which also includes pangolins) in the tenth edition of his book Systema Naturae . He recognized six genera: Canis (canids and hyaenids), Phoca (pinnipeds), Felis (felids), Viverra (viverrids, herpestids, and mephitids), Mustela (non-badger mustelids), Ursus (ursids, large species of mustelids, and procyonids). It

3920-478: The family Mustelidae include: 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. Mustelid species diversity is often attributed to an adaptive radiation coinciding with

4000-449: The first three months of life, otter pups cannot swim or dive effectively. They are born with a natal pelage that differs in color and structure from adult pelage and is incredibly buoyant. This prevents them from submerging their bodies underwater and must be held or anchored to kelp . Sea otter pups display a propensity for manipulating objects between their paws and regularly pound rocks and little bits of coral against their bodies in

4080-439: The forelimbs or teeth. Shellfish are found on rock structures at the bottom of the ocean, so collecting multiple rocks and shellfish from the bottom of the ocean in one diving episode and crushing the objects together on the surface may have led to the association of rocks with crushing shells of foods items. If a behavior which was performed in a conflict situation happened to open a prey item, an otter may have attempted to repeat

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4160-612: The forelimbs. Among tool using otters, up to 21% of the day can be spent engaging in tool use. In a study conducted from Alaska to Southern California, sixteen otter populations demonstrated that individual diet specializations are much more likely to be present in environments of rocky habitat over soft sediment substrates. Daughter Californian otters display the same tool techniques as their mothers, expressing explicit preference for certain methods when eating bivalves or eating crabs. In an aforementioned study, which compiled 17 years of observational data on otters from southern California to

4240-407: The front of the face. In caniforms, the rostrum is usually long with many teeth, while in feliforms it is shorter with fewer teeth. The carnassial teeth of feliforms are generally more sectional than those of caniforms. The turbinates are large and complex in comparison to other mammals, providing a large surface area for olfactory receptors . Aside from an accumulation of characteristics in

4320-438: The fur brought to market. One species, the sea mink ( Neogale macrodon ) of New England and Canada, was driven to extinction 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

4400-518: The indirect effects of overfishing; the black-footed ferret , a relative of the European polecat , suffers from the loss of American prairie ; and wolverine populations are slowly declining because of habitat destruction and persecution. The rare European mink ( Mustela lutreola ) is one of the most endangered mustelid species. The ferret , a domesticated European polecat, is a fairly common pet . The oldest known mustelid from North America

4480-442: The largest lungs in the otter family, which may be helpful for buoyancy , especially because sea otters do not have blubber . Being buoyant along the length of the body allows otters to lie on their backs and manipulate food, tools, and young while on the surface of the water. Underneath the arm of each sea otter, at the axilla, is a flap of skin that can store stones and food. The hind legs are long and flattened like flippers, and

4560-720: 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 Mellivorinae Subfamily Melinae Subfamily Helictidinae Subfamily Guloninae Subfamily Ictonychinae Subfamily Lutrinae ( otters ) Subfamily Mustelinae (weasels, ferrets, and mink) Fossil mustelids Extinct genera of

4640-407: The limbs have been modified into flippers . Unlike cetaceans and sirenians , which have fully functional tails to help them swim, pinnipeds use their limbs underwater to swim. Earless seals use their back flippers; sea lions and fur seals use their front flippers, and the walrus uses all of its limbs. As a result, pinnipeds have significantly shorter tails than other carnivorans. Aside from

4720-536: The methods in which mammalogists use to assess the phylogenetic relationships among the carnivoran families has been improved with using more complicated and intensive incorporation of genetics, morphology and the fossil record. Research into Carnivora phylogeny since 1945 has found Fisspedia to be paraphyletic in respect to Pinnipedia, with pinnipeds being either more closely related to bears or to weasels. The small carnivoran families Viverridae, Procyonidae, and Mustelidae have been found to be polyphyletic : Below

4800-410: The most dominant group of large terrestrial predators in Eurasia and North America, with various lineages being successful in megafaunal faunivorous niches at different intervals during the Miocene and later epochs. The order Carnivora belongs to a group of mammals known as Laurasiatheria , which also includes other groups such as bats and ungulates . Within this group the carnivorans are placed in

4880-610: The mothers at all times. Otter pups therefore receive undivided attention from their mothers for prolonged periods of time. Similarly, young otters are observed to be exceptionally active, curious, and playful. Selection may have favored certain kinds of manipulatory play. Sea otters belong to the order Carnivora , whose members possess typical carnivoran teeth, or shearing carnassials . These are blade-like teeth formed by an upper premolar and lower molar . Sea otters have replaced their carnassial teeth with bunodont post-canines to improve their food crushing ability. These teeth favor

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4960-442: The nature of the carnassial teeth is different between the two groups. In carnivorans the carnassials are positioned near the front of the molar row, while in the creodonts they are positioned near the back of the molar row, and this suggests a separate evolutionary history and an order-level distinction. In addition, recent phylogenetic analysis suggests that creodonts are more closely related to pangolins while mesonychians might be

5040-551: 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 , they all possess teeth adapted for eating flesh, including

5120-744: The only exception, occurring in the old world and the new world, entering the Americas via the Bering Land Bridge. The caniforms include the Caninae , Procyonidae , bears , mustelids , skunks and pinnipeds that occur worldwide with immense diversity in their morphology, diet and behavior. The word carnivore is derived from Latin carō (stem carn- ) 'flesh' and vorāre 'to devour', and refers to any meat-eating organism. The oldest known carnivoran line mammals ( Carnivoramorpha ) appeared in North America 6 million years after

5200-783: The pinnipeds, dogs, bears, hyenas, and cats all have distinct and recognizable appearances. Dogs are usually cursorial mammals and are gracile in appearance, often relying on their teeth to hold prey; bears are much larger and rely on their physical strength to forage for food. Compared to dogs and bears, cats have longer and stronger forelimbs armed with retractable claws to hold on to prey. Hyenas are dog-like feliforms that have sloping backs due to their front legs being longer than their hind legs. The raccoon family and red panda are small, bear-like carnivorans with long tails. The other small carnivoran families Nandiniidae , Prionodontidae , Viverridae , Herpestidae , Eupleridae, Mephitidae and Mustelidae have through convergent evolution maintained

5280-436: The presence of shearing carnassials . 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 3.1.3.1 3.1.3.2 . The fisher , tayra, and martens are partially arboreal, while badgers are fossorial . A number of mustelids have aquatic lifestyles, ranging from semiaquatic minks and river otters to

5360-403: The process of evolution, which led to this adaptation. The first instance of a rock as a tool may have occurred when an otter was unable to access a prey item at the bottom of the ocean and used a rock to facilitate access to the object. Similarly, an otter at the surface of the water may have chosen to crush two bivalves against each other when faced with an inability to crush the prey items with

5440-430: The same rock as they learn to swim. Otters forage independently, except for females with offspring, who feed with their single young. Twins are observed but very rare. This allows for the mother otters to focus their attention on the pup, especially because mating occurs without pair bonding, so the father of the pup is not present. Pups express the same preferences in tools, technique, and diet as their mothers, which

5520-408: The sea otter they have anal scent glands that produce a strong-smelling secretion the animals use for sexual signalling and marking territory . Most mustelid reproduction involves embryonic diapause . The embryo does not immediately implant in the uterus , but remains dormant for some time. No development takes place as long as the embryo remains unattached to the uterine lining. As a result,

5600-465: The sister group to carnivorans and their stem-relatives. The closest stem-carnivorans are the miacoids . The miacoids include the families Viverravidae and Miacidae , and together the Carnivora and Miacoidea form the stem-clade Carnivoramorpha . The miacoids were small, genet-like carnivoramorphs that occupy a variety of niches such as terrestrial and arboreal habitats. Recent studies have shown

5680-406: The small, ancestral appearance of the miacoids, though there is some variation seen such as the robust and stout physicality of badgers and the wolverine ( Gulo gulo ). Most carnivoran species have a well-defined breeding season . Male carnivorans usually have bacula , which are absent in hyenas and binturongs . The length and density of the fur vary depending on the environment that

5760-491: The southern Pacific Ocean feed on tougher macro invertebrates such as bivalves. In central California, sea otters feed mostly on sea urchins , abalones , and rock crabs . Rocks are used to knock abalones from the structure on which they are growing. Rocks can also be used to crack crab carapaces . Scientists have studied areas of California where up to 80% of abalone shells display crack patterns that are suggestive of breakage against rocks performed by otters. In areas near

5840-433: The species inhabits. In warm climate species, the fur is often short in length and lighter. In cold climate species, the fur is either dense or long, often with an oily substance that helps to retain heat. The pelage coloration differs between species, often including black, white, orange, yellow, red, and many shades of grey and brown. Some are striped, spotted, blotched, banded, or otherwise boldly patterned. There seems to be

5920-472: The subject, and serving as a model for what kinds of tool use behaviors the sea otter species is capable of performing. Sea otters do not seem to express preference for stones and rocks of a particular shape (smooth, sharp, flat, irregular), instead choosing ones that fall between a size range of 6–15 cm (2.4–5.9 in), suggesting that size is more important than shape. Otters go on dives with their tools stored in specialized pouches of skin underneath

6000-460: The tail is also flattened. The tail moves in an undulating motion for propulsion. Paws and vibrissae work in tandem to find and grasp prey underwater. It was found that orphaned juvenile sea otters in a research facility spontaneously developed stone tool use, without observing any models. Relatedly, stone handling behaviours were observed in 10 out of the 13 currently known subspecies of otters, including sea otters. Together, both studies suggest

6080-431: The tool use behavior may have spread through a population of nearby otters by horizontal social learning. Tool use behaviors are observed in mammalian species where adults and their progeny have close ties. Mother otters have one pup at a time and sea otter pups are dependent on their mothers for an average of 6 to 7 months. Extremely young pups cannot swim or dive due to their natal fur coating, so they must be anchored to

6160-404: The wrapped crabs on the chest while the otter eats other kinds of collected prey from the ocean bottom. Sea otters are familiar with kelp as a wrapping agent because they wrap themselves in kelp to remain in one location at the surface during periods of rest, or during sleeping. Mother otters also wrap their offspring in kelp when they cannot rest the pups on their chests. Intra-species variation

6240-486: Was not until 1821 that the English writer and traveler Thomas Edward Bowdich gave the group its modern and accepted name. Initially, the modern concept of Carnivora was divided into two suborders: the terrestrial Fissipedia and the marine Pinnipedia . Below is the classification of how the extant families were related to each other after American paleontologist George Gaylord Simpson in 1945: Since then, however,

6320-689: Was often of poor quality because the mothers frequently foraged on prey items that are easily captured by pups". The foundation for observation studies of otters was conducted by scientists K. R. L. Hall and George B. Schaller in 1964. The scientists spent six days observing the Californian otters in Point Lobos State Park, California. Over the course of their time, they observed 30 separate instances of tool use behaviors, most of which involved otters using rocks to crack mussels. Since then, Californian sea otters have been studied extensively for their tool use behavior, garnering more attention to

6400-403: Was seen than one otter ate 44 mussels in one feeding episode and only used six stones. Sea otter development is marked by a six-month-long dependency period. Once an otter has adult-like swimming and diving behavior, can procure food by itself, and self-groom, it is considered independent. Until then, otter pups spend all of their time with their mothers. This is exacerbated by the fact that for

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