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86-704: The rodent parvorder or infraorder Phiomorpha comprises several living and extinct families found wholly or largely in Africa . Along with Anomaluromorpha and perhaps the extinct Zegdoumyidae , it represents one of the few early colonizations of Africa by rodents. During the Oligocene , Africa was not connected to any of the other continents. The predominant theory suggests that rodents first evolved in Laurasia , and expanded outward from there. Although Europe , Asia , and North America were distinct landmasses during much of
172-414: A burrow and one male defending a territory around the burrow. At high population densities, this system breaks down and males show a hierarchical system of dominance with overlapping ranges. Female offspring remain in the colony while male young disperse. The prairie vole is monogamous and forms a lifelong pair bond. Outside the breeding season, prairie voles live with others in small colonies. A male
258-491: A colony of their own. Rodents use scent marking in many social contexts including inter- and intra-species communication, the marking of trails and the establishment of territories. Their urine provides genetic information about individuals including the species, the sex and individual identity, and metabolic information on dominance, reproductive status and health. Compounds derived from the major histocompatibility complex (MHC) are bound to several urinary proteins. The odor of
344-406: A distinct "chirping", has been likened to laughter , and is interpreted as an expectation of something rewarding. In clinical studies, the chirping is associated with positive emotional feelings, and social bonding occurs with the tickler, resulting in the rats becoming conditioned to seek the tickling. However, as the rats age, the tendency to chirp declines. Like most rat vocalizations, the chirping
430-485: A few are predators. The field vole is a typical herbivorous rodent and feeds on grasses, herbs, root tubers, moss, and other vegetation, and gnaws on bark during the winter. It occasionally eats invertebrates such as insect larvae. The plains pocket gopher eats plant material found underground during tunneling, and also collects grasses, roots, and tubers in its cheek pouches and caches them in underground larder chambers. The Texas pocket gopher avoids emerging onto
516-575: A few have become specialized to rely on a diet of animal matter. A functional-morphological study of the rodent tooth system supports the idea that primitive rodents were omnivores rather than herbivores. Studies of the literature show that numerous members of the Sciuromorpha and Myomorpha, and a few members of the Hystricomorpha, have either included animal matter in their diets or been prepared to eat such food when offered it in captivity. Examination of
602-444: A high-fiber diet; their molars have no roots and grow continuously like their incisors. In many species, the molars are relatively large, intricately structured, and highly cusped or ridged. Rodent molars are well equipped to grind food into small particles. The jaw musculature is strong. The lower jaw is thrust forward while gnawing and is pulled backwards during chewing. Gnawing uses incisors and chewing uses molars, however, due to
688-535: A means of intra-specific communication during courtship among the Cape mole rat . Footdrumming has been reported to be involved in male-male competition; the dominant male indicates its resource holding potential by drumming, thus minimizing physical contact with potential rivals. Some species of rodent are monogamous, with an adult male and female forming a lasting pair bond . Monogamy can come in two forms; obligate and facultative. In obligate monogamy, both parents care for
774-611: A moderately fused postorbital process to the cranium , unlike other small mammals. They differ in that they have a mixture of "basal" and "derived" physical traits. Lagomorphs and rodents form the clade or grandorder Glires . Despite the evolutionary relationship between lagomorphs and rodents, the two orders have some major differences. Lagomorphs have four incisors in the upper jaw (smaller peg teeth behind larger incisors), whereas rodents only have two. They are similar to rodents in that their incisors grow continuously, thus necessitating constant chewing on fibrous food to prevent
860-684: A mutual territory. Pikas are diurnal and are active early and late in the day during hot weather. They feed on all sorts of plant material. As they do not hibernate, they make "haypiles" of dried vegetation which they collect and carry back to their homes to store for use during winter. Hares, members of genus Lepus of family Leporidae, are medium size mammals native to Europe, Asia, Africa, and North America. North American jackrabbits are actually hares. Species vary in size from 40 to 70 cm (16 to 28 in) in length and have long powerful back legs, and ears up to 20 cm (8 in) in length. Although usually greyish-brown, some species turn white in
946-686: A part in social communication between dormice and are used when the individuals are out of sight of each other. House mice use both audible and ultrasonic calls in a variety of contexts. Audible vocalizations can often be heard during agonistic or aggressive encounters, whereas ultrasound is used in sexual communication and also by pups when they have fallen out of the nest. Laboratory rats (which are brown rats, Rattus norvegicus ) emit short, high frequency, ultrasonic vocalizations during purportedly pleasurable experiences such as rough-and-tumble play, when anticipating routine doses of morphine , during mating, and when tickled. The vocalization, described as
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#17328592082511032-455: A predator depresses scent-marking behavior. Rodents are able to recognize close relatives by smell and this allows them to show nepotism (preferential behavior toward their kin) and also avoid inbreeding. This kin recognition is by olfactory cues from urine, feces and glandular secretions. The main assessment may involve the MHC, where the degree of relatedness of two individuals is correlated to
1118-499: A predator warning or defensive action. It is used primarily by fossorial or semi-fossorial rodents. The banner-tailed kangaroo rat produces several complex footdrumming patterns in a number of different contexts, one of which is when it encounters a snake. The footdrumming may alert nearby offspring but most likely conveys that the rat is too alert for a successful attack, thus preventing the snake's predatory pursuit. Several studies have indicated intentional use of ground vibrations as
1204-403: A single female monopolizes mating from at least three males. In most rodent species, such as brown rats and house mice, ovulation occurs on a regular cycle while in others, such as voles, it is induced by mating . During copulation, males of some rodent species deposit a mating plug in the female's genital opening, both to prevent sperm leakage and to protect against other males inseminating
1290-412: A single upper and lower pair of ever-growing incisors. Well-known rodents include mice , rats , squirrels , prairie dogs , porcupines , beavers , guinea pigs , and hamsters . However, rabbits , hares , and pikas , which also have incisors that grow continuously (but have two pairs of upper incisors instead of one), were once included with rodents, but are now considered to be in a separate order,
1376-549: A small part of its diet is plant material. It has a chunky body with short legs and tail, but is agile and can easily overpower prey as large as itself. Rodents exhibit a wide range of types of social behavior ranging from the mammalian caste system of the naked mole-rat , the extensive "town" of the colonial prairie dog , through family groups to the independent, solitary life of the edible dormouse . Adult dormice may have overlapping feeding ranges, but they live in individual nests and feed separately, coming together briefly in
1462-429: A wider variety of colours. Newborn rabbits are altricial (eyes and ears closed, no fur). Although most species live in burrows, the cottontails and hispid hares have forms (nests above ground, usually under a bush). Most of the burrowing species are colonial, and feed together in small groups. Rabbits play an important part in the terrestrial food chain , eating a wide range of forbs , grasses, and herbs, and being part of
1548-404: Is at frequencies too high for humans to hear without special equipment, so bat detectors have been used for this purpose. Rodents, like all placental mammals except primates, have just two types of light receptive cones in their retina, a short wavelength "blue-UV" type and a middle wavelength "green" type. They are therefore classified as dichromats ; however, they are visually sensitive into
1634-641: Is evident in particular subgroups of rodents like kangaroo rats , hamsters, chipmunks and gophers which have two bags that may range from the mouth to the front of the shoulders. True mice and rats do not contain this structure but their cheeks are elastic due to a high degree of musculature and innervation in the region. While the largest species, the capybara , can weigh as much as 66 kg (146 lb), most rodents weigh less than 100 g (3.5 oz). Rodents have wide-ranging morphologies, but typically have squat bodies and short limbs. The fore limbs usually have five digits, including an opposable thumb, while
1720-402: Is mostly driven by the brain stem, which is itself provoked by the cortex. However Legg et al. 1989 find an alternate circuit between the cortex and whiskers through the cerebellar circuits, and Hemelt & Keller 2008 the superior colliculus. Some rodents have cheek pouches , which may be lined with fur. These can be turned inside out for cleaning. In many species, the tongue cannot reach past
1806-915: Is not aggressive towards other males until he has mated, after which time he defends a territory, a female, and a nest against other males. The pair huddles together, grooms one another, and shares nesting and pup-raising responsibilities. Among the most social of rodents are the ground squirrels, which typically form colonies based on female kinship, with males dispersing after weaning and becoming nomadic as adults. Cooperation in ground squirrels varies between species and typically includes making alarm calls, defending territories, sharing food, protecting nesting areas, and preventing infanticide. The black-tailed prairie dog forms large towns that may cover many hectares. The burrows do not interconnect, but are excavated and occupied by territorial family groups known as coteries. A coterie often consists of an adult male, three or four adult females, several nonbreeding yearlings, and
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#17328592082511892-400: Is not understood why this pattern occurs, but in the case of yellow-pine chipmunks , males may have selected larger females due to their greater reproductive success. In some species, such as voles , sexual dimorphism can vary from population to population. In bank voles , females are typically larger than males, but male-bias sexual dimorphism occurs in alpine populations, possibly because of
1978-532: Is some question as to whether these mothers can distinguish which young are theirs. In the Patagonian mara , young are also placed in communal warrens, but mothers do not permit youngsters other than their own to nurse. Infanticide exists in numerous rodent species and may be practiced by adult conspecifics of either sex. Several reasons have been proposed for this behavior, including nutritional stress, resource competition, avoiding misdirecting parental care and, in
2064-406: The Cape ground squirrel , the male's testes can be 20 percent of its head-body length. Several rodent species have flexible mating systems that can vary between monogamy, polygyny and promiscuity. Female rodents play an active role in choosing their mates. Factors that contribute to female preference may include the size, dominance and spatial ability of the male. In the eusocial naked mole rats,
2150-626: The Eocene and Oligocene, they experienced intermittent migration events across the shallow sea separating Europe and Asia, via an ice-free Greenland (Europe and North America), or across Beringia (North America and Asia). The southern continents were much more isolated leading to the unique faunas of Australia , South America , and to a lesser degree Africa. Although the hystricognath rodents may have evolved from an early entodacryan ancestor in Asia, they migrated to Africa soon after. Phiomorpha represents
2236-599: The Great Plains of North America, the burrowing activities of prairie dogs play important roles in soil aeration and nutrient redistribution, raising the organic content of the soil and increasing the absorption of water. They maintain these grassland habitats, and some large herbivores such as bison and pronghorn prefer to graze near prairie dog colonies due to the increased nutritional quality of forage. Extirpation of prairie dogs can also contribute to regional and local biodiversity loss , increased seed depredation, and
2322-805: The Lagomorpha . Nonetheless, Rodentia and Lagomorpha are sister groups , sharing a single common ancestor and forming the clade of Glires . Most rodents are small animals with robust bodies, short limbs, and long tails. They use their sharp incisors to gnaw food, excavate burrows, and defend themselves. Most eat seeds or other plant material, but some have more varied diets. They tend to be social animals and many species live in societies with complex ways of communicating with each other. Mating among rodents can vary from monogamy , to polygyny , to promiscuity . Many have litters of underdeveloped, altricial young, while others are precocial (relatively well developed) at birth. The rodent fossil record dates back to
2408-620: The Laotian rock rat (family Diatomyidae ); also, more recent evidence not supports them belonging in Phiomorpha. Molecular results suggest that the Diatomyidae is a part of the Ctenodactylomorphi , but this is in contrast to morphological results which place the animal at a basal position to all hystricognaths. Rodent Rodents (from Latin rodere , 'to gnaw') are mammals of
2494-528: The Paleocene on the supercontinent of Laurasia . Rodents greatly diversified in the Eocene , as they spread across continents, sometimes even crossing oceans . Rodents reached both South America and Madagascar from Africa and, until the arrival of Homo sapiens , were the only terrestrial placental mammals to reach and colonize Australia. Rodents have been used as food, for clothing, as pets , and as laboratory animals in research. Some species, in particular,
2580-408: The brown rat , the black rat , and the house mouse , are serious pests , eating and spoiling food stored by humans and spreading diseases. Accidentally introduced species of rodents are often considered to be invasive and have caused the extinction of numerous species, such as island birds, the dodo being an example, previously isolated from land-based predators. The distinguishing feature of
2666-608: The clade that evolved as a result. Although once diverse, this infraorder is now restricted to the Old World porcupines , the cane rats , the dassie rat , the naked mole-rat , and the blesmols . The makeup of this infraorder is controversial. At its core lie the extant families Thryonomyidae , Petromuridae , and Bathyergidae and their extinct relatives. The Old World porcupines (Hystricidae) are sometimes included in Phiomorpha, but many authorities consider them either basal to all hystricognaths or basal to all hystricognaths except
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2752-410: The eastern grey squirrel , have a large deep masseter , making them efficient at biting with the incisors. The Myomorpha , such as the brown rat, have enlarged temporalis and masseter muscles, making them able to chew powerfully with their molars. In rodents, masseter muscles insert behind the eyes and contribute to eye boggling that occurs during gnawing where the quick contraction and relaxation of
2838-429: The hispid hare . They are native to Europe, parts of Africa, Central and Southern Asia, North America and much of South America. They inhabit both grassland and arid regions. They vary in size from 20 to 50 cm (8 to 20 in) and have long, powerful hind legs, shorter forelegs and a tiny tail. The colour is some shade of brown, buff or grey and there is one black species and two striped ones. Domestic rabbits come in
2924-785: The order Rodentia ( / r oʊ ˈ d ɛ n ʃ ə / roh- DEN -shə ), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws . About 40% of all mammal species are rodents. They are native to all major land masses except for Antarctica , and several oceanic islands, though they have subsequently been introduced to most of these land masses by human activity. Rodents are extremely diverse in their ecology and lifestyles and can be found in almost every terrestrial habitat, including human-made environments. Species can be arboreal , fossorial (burrowing), saltatorial /ricochetal (leaping on their hind legs), or semiaquatic. However, all rodents share several morphological features, including having only
3010-621: The MHC genes they have in common. In non-kin communication, where more permanent odor markers are required, as at territorial borders, then non-volatile major urinary proteins (MUPs), which function as pheromone transporters, may also be used. MUPs may also signal individual identity, with each male house mouse ( Mus musculus ) excreting urine containing about a dozen genetically encoded MUPs. House mice deposit urine, which contains pheromones, for territorial marking, individual and group recognition, and social organization. Territorial beavers and red squirrels investigate and become familiar with
3096-441: The amount of UV that is reflected decreases with time, which in some circumstances can be disadvantageous; the common kestrel can distinguish between old and fresh rodent trails and has greater success hunting over more recently marked routes. Vibrations can provide cues to conspecifics about specific behaviors being performed, predator warning and avoidance, herd or group maintenance, and courtship. The Middle East blind mole rat
3182-411: The bottoms of their paws are entirely covered with fur, a trait they share with red pandas . Similar to the rodents, bats , and some mammalian insectivores , they have a smooth-surfaced cerebrum . Lagomorphs are unusual among terrestrial mammals in that the females are larger than males. Rabbits and hares move by jumping, pushing off with their strong hind legs and using their forelimbs to soften
3268-524: The breeding season to mate. The pocket gopher is also a solitary animal outside the breeding season, each individual digging a complex tunnel system and maintaining a territory. Larger rodents tend to live in family units where parents and their offspring live together until the young disperse. Beavers live in extended family units typically with a pair of adults, this year's kits, the previous year's offspring, and sometimes older young. Brown rats usually live in small colonies with up to six females sharing
3354-709: The case of males, attempting to make the mother sexually receptive. The latter reason is well supported in primates and lions but less so in rodents. Infanticide appears to be widespread in black-tailed prairie dogs, including infanticide from invading males and immigrant females, as well as occasional cannibalism of an individual's own offspring. To protect against infanticide from other adults, female rodents may employ avoidance or direct aggression against potential perpetrators, multiple mating, territoriality or early termination of pregnancy. Feticide can also occur among rodents; in Alpine marmots , dominant females tend to suppress
3440-463: The country and caused disruption to native species. Easily digestible food is processed in the gastrointestinal tract and expelled as regular feces. But in order to get nutrients out of hard to digest fiber, lagomorphs ferment fiber in the cecum (in the GI tract) and then expel the contents as cecotropes , which are reingested ( cecotrophy ). The cecotropes are then absorbed in the small intestine to utilize
3526-479: The cranial anatomy of rodents these feeding methods cannot be used at the same time and are considered to be mutually exclusive. Among rodents, the masseter muscle plays a key role in chewing, making up 60% – 80% of the total muscle mass among masticatory muscles and reflects rodents' herbivorous diet. Rodent groups differ in the arrangement of the jaw muscles and associated skull structures, both from other mammals and amongst themselves. The Sciuromorpha , such as
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3612-412: The current year's offspring. Individuals within coteries are friendly with each other, but hostile towards outsiders. Perhaps the most extreme examples of colonial behavior in rodents are the eusocial naked mole rat and Damaraland mole rat . The naked mole rat lives completely underground and can form colonies of up to 80 individuals. Only one female and up to three males in the colony reproduce, while
3698-594: The degu less visible to predators. Ultraviolet light is abundant during the day but not at night. There is a large increase in the ratio of ultraviolet to visible light in the morning and evening twilight hours. Many rodents are active during twilight hours (crepuscular activity), and UV-sensitivity would be advantageous at these times. Ultraviolet reflectivity is of dubious value for nocturnal rodents. The urine of many rodents (e.g. voles, degus, mice, rats) strongly reflects UV light and this may be used in communication by leaving visible as well as olfactory markings. However,
3784-489: The establishment and spread of invasive shrubs. Burrowing rodents may eat the fruiting bodies of fungi and spread spores through their feces, thereby allowing the fungi to disperse and form symbiotic relationships with the roots of plants (which usually cannot thrive without them). As such, these rodents may play a role in maintaining healthy forests. In many temperate regions, beavers play an essential hydrological role. When building their dams and lodges, beavers alter
3870-669: The family Ochotonidae and are small mammals native to mountainous regions of western North America and Central Asia. They are mostly about 15 cm (6 in) long and have greyish-brown, silky fur, small rounded ears, and almost no tail. Their four legs are nearly equal in length. Some species live in scree , making their homes in the crevices between broken rocks, while others construct burrows in upland areas. The rock-dwelling species are typically long-lived and solitary, having one or two small litters each year contributing to stable populations. The burrowing species, in contrast, are short-lived, gregarious and have multiple large litters during
3956-812: The female. Females can remove the plug and may do so either immediately or after several hours. Metabolism of thyroid hormones and iodine in the mediobasal hypothalamus changes in response to photoperiod . Thyroid hormones in turn induce reproductive changes. This is found by Watanabe et al. 2004 and 2007, Barrett et al. 2007, Freeman et al. 2007, and Herwig et al. 2009 in Siberian hamsters , Revel et al. 2006 and Yasuo et al. 2007 in Syrian hamsters , Yasuo et al. 2007 and Ross et al. 2011 in rats, and Ono et al. 2008 in mice. Rodents may be born either altricial (blind, hairless and relatively underdeveloped) or precocial (mostly furred, eyes open and fairly developed) depending on
4042-498: The females that live within the territories are known as "resident" females. In the case of marmots, resident males do not appear to ever lose their territories and always win encounters with invading males. Some species are also known to directly defend their resident females and the ensuing fights can lead to severe wounding. In species with non-defense polygyny, males are not territorial and wander widely in search of females to monopolize. These males establish dominance hierarchies, with
4128-513: The few animal groups that can break open the large capsules of the Brazil nut fruit. Too many seeds are inside to be consumed in one meal, so the agouti carries some off and caches them. This helps dispersal of the seeds as any that the agouti fails to retrieve are distant from the parent tree when they germinate. Other nut-bearing trees tend to bear a glut of fruits in the autumn. These are too numerous to be eaten in one meal and squirrels gather and store
4214-600: The finding that rodents entirely lack the ability to vomit. In many species, the penis contains a bone, the baculum ; the testes can be located either abdominally or at the groin. Sexual dimorphism occurs in many rodent species. In some rodents, males are larger than females, while in others the reverse is true. Male-bias sexual dimorphism is typical for ground squirrels , kangaroo rats, solitary mole rats and pocket gophers ; it likely developed due to sexual selection and greater male–male combat. Female-bias sexual dimorphism exists among chipmunks and jumping mice . It
4300-463: The fore to the hind limbs. The agouti is fleet-footed and antelope -like, being digitigrade and having hoof-like nails. The majority of rodents have tails, which can be of many shapes and sizes. Some tails are prehensile , as in the Eurasian harvest mouse , and the fur on the tails can vary from bushy to completely bald. The tail is sometimes used for communication, as when beavers slap their tails on
4386-444: The high-ranking males having access to the most females. This occurs in species like Belding's ground squirrels and some tree squirrel species. Promiscuity , in which both males and females mate with multiple partners, also occurs in rodents. In species such as the white-footed mouse, females give birth to litters with multiple paternities. Promiscuity leads to increased sperm competition and males tend to have larger testicles. In
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#17328592082514472-690: The hind limbs have three to five digits. The elbow gives the forearms great flexibility. The majority of species are plantigrade , walking on both the palms and soles of their feet, and have claw-like nails. The nails of burrowing species tend to be long and strong, while arboreal rodents have shorter, sharper nails. Rodent species use a wide variety of methods of locomotion including quadrupedal walking, running, burrowing, climbing, bipedal hopping ( kangaroo rats and hopping mice ), swimming and even gliding. Scaly-tailed squirrels and flying squirrels , although not closely related, can both glide from tree to tree using parachute-like membranes that stretch from
4558-420: The impact on landing. Pikas lack certain skeletal modifications present in leporids , such as a highly arched skull, an upright posture of the head, strong hind limbs and pelvic girdle, and long limbs. Also, pikas have a short nasal region and entirely lack a supraorbital foramen , while leporids have prominent supraorbital foramina and nasal regions. Pikas , also known as conies, are entirely represented by
4644-442: The incisors. Rodents have efficient digestive systems, absorbing nearly 80% of ingested energy. When eating cellulose , the food is softened in the stomach and passed to the cecum , where bacteria reduce it to its carbohydrate elements. The rodent then practices coprophagy , eating its own fecal pellets, so the nutrients can be absorbed by the gut. Rodents therefore often produce a hard and dry fecal pellet. Horn et al. 2013 makes
4730-812: The lack of predators and greater competition between males. One of the most widespread groups of mammals, rodents can be found on every continent except Antarctica. They are the only terrestrial placental mammals to have colonized Australia and New Guinea without human intervention. Humans have also allowed the animals to spread to many remote oceanic islands (e.g., the Polynesian rat ). Rodents have adapted to almost every terrestrial habitat, from cold tundra (where they can live under snow) to hot deserts. Some species such as tree squirrels and New World porcupines are arboreal , while some, such as gophers , tuco-tucos , and mole rats, live almost completely underground, where they build complex burrow systems. Others dwell on
4816-583: The lagomorphs is still not well understood. In the late 20th century, it was generally agreed that Eurymylus , which lived in eastern Asia and dates back to the late Paleocene or early Eocene , was an ancestor of the lagomorphs. Examination of the fossil evidence in the 21st century suggested that the lagomorphs may have instead descended from mimotonids, mammals present in Asia during the Paleogene with similar body size and dental structure to early European rabbits such as Megalagus turgidus , while Eurymylus
4902-502: The leaves, buds, and inner bark of growing trees, as well as aquatic plants. They store food for winter use by felling small trees and leafy branches in the autumn and immersing them in their pond, sticking the ends into the mud to anchor them. Here, they can access their food supply underwater even when their pond is frozen over. Although rodents have been regarded traditionally as herbivores, most small rodents opportunistically include insects, worms, fungi, fish, or meat in their diets and
4988-760: The males do not provide direct parental care and stay with one female because they cannot access others due to being spatially dispersed. Prairie voles appear to be an example of this form of monogamy, with males guarding and defending females within their vicinity. In polygynous species, males will try to monopolize and mate with multiple females. As with monogamy, polygyny in rodents can come in two forms; defense and non-defense. Defense polygyny involves males controlling territories that contain resources that attract females. This occurs in ground squirrels like yellow-bellied marmots , California ground squirrels , Columbian ground squirrels and Richardson's ground squirrels . Males with territories are known as "resident" males and
5074-896: The members of the taxonomic order Lagomorpha , of which there are two living families : the Leporidae ( rabbits and hares ) and the Ochotonidae ( pikas ). There are 110 recent species of lagomorph of which 109 are extant, including 10 genera of rabbits (42 species), 1 genus of hare (33 species) and 1 genus of pika (34 species). The name of the order is derived from the Ancient Greek lagos (λαγώς, "hare") + morphē (μορφή, "form"). Other names used for this order, now considered synonymous , include: Duplicidentata (Illiger, 1811); Leporida (Averianov, 1999); Neolagomorpha (Averianov, 1999); Ochotonida (Averianov, 1999); and Palarodentia (Haeckel, 1895; Lilian, 2016). The evolutionary history of
5160-430: The mother only visits and feeds the litter once a day but the young grow rapidly and are usually weaned within a month. Hare young are called leverets. Adults have a strategy to prevent predators from tracking down their litter by following the adults' scent. They approach and depart from the nesting site in a series of immense bounds, sometimes moving at right angles to their previous direction. Each litter of hares have
5246-451: The muscle causes the eyeballs to move up and down. The Hystricomorpha , such as the guinea pig, have larger superficial masseter muscles and smaller deep masseter muscles than rats or squirrels, possibly making them less efficient at biting with the incisors, but their enlarged internal pterygoid muscles may allow them to move the jaw further sideways when chewing. The cheek pouch is a specific morphological feature used for storing food and
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#17328592082515332-521: The nature of the precise threat. The urgency of the threat is also conveyed by the acoustic properties of the call. Social rodents have a wider range of vocalizations than do solitary species. Fifteen different call-types have been recognized in adult Kataba mole rats and four in juveniles. Similarly, the common degu , another social, burrowing rodent, exhibits a wide array of communication methods and has an elaborate vocal repertoire comprising fifteen different categories of sound. Ultrasonic calls play
5418-675: The nest a few days after they have opened their eyes and initially keep returning regularly. As they get older and more developed, they visit the nest less often and leave permanently when weaned. In precocial species, the mothers invest little in nest building and some do not build nests at all. The female gives birth standing and the young emerge behind her. Mothers of these species maintain contact with their highly mobile young with maternal contact calls. Though relatively independent and weaned within days, precocial young may continue to nurse and be groomed by their mothers. Rodent litter sizes also vary and females with smaller litters spend more time in
5504-564: The nest than those with larger litters. Mother rodents provide both direct parental care, such as nursing, grooming, retrieving and huddling, and indirect parenting, such as food caching, nest building and protection to their offspring. In many social species, young may be cared for by individuals other than their parents, a practice known as alloparenting or cooperative breeding . This is known to occur in black-tailed prairie dogs and Belding's ground squirrels, where mothers have communal nests and nurse unrelated young along with their own. There
5590-560: The nutrients. Like rodents, they are not able to vomit. Many lagomorphs breed several times a year and produce large litters. This is particularly the case in species that live in underground, protective environments, such as burrows. The young of rabbits and pikas (called kits) are born after a short gestation period and the mother can become pregnant again almost immediately after giving birth. The mothers are able to leave these young safely and go off to feed, returning at intervals to feed them with their unusually rich milk. In some species,
5676-437: The offspring and play an important part in their survival. This occurs in species such as California mice , oldfield mice , Malagasy giant rats and beavers. In these species, males usually mate only with their partners. In addition to increased care for young, obligate monogamy can also be beneficial to the adult male as it decreases the chances of never finding a mate or mating with an infertile female. In facultative monogamy,
5762-518: The paths of streams and rivers and allow for the creation of extensive wetland habitats. One study found that engineering by beavers leads to a 33 percent increase in the number of herbaceous plant species in riparian areas . Another study found that beavers increase wild salmon populations. Meanwhile, some rodents are seen as pests , due to their wide range. Most rodents are herbivorous , feeding exclusively on plant material such as seeds, stems, leaves, flowers, and roots. Some are omnivorous and
5848-514: The present, with around 75 genera and over 230 species represented in the fossil record and many more species in a single biome . This is evidence that lagomorph lineages are declining. A 2008 study suggests an Indian origin for the order, having possibly evolved in isolation when India was an island continent in the Paleocene . Lagomorphs are similar to other mammals in that they all have hair, four limbs (i.e., they are tetrapods ), and mammary glands and are endotherms . Lagomorphs possess
5934-545: The reproduction of subordinates by being antagonistic towards them while they are pregnant. The resulting stress causes the fetuses to abort. Rodents have advanced cognitive abilities. They can quickly learn to avoid poisoned baits, which makes them difficult pests to deal with. Guinea pigs can learn and remember complex pathways to food. Squirrels and kangaroo rats are able to locate caches of food by spatial memory , rather than just by smell. Lagomorpha The lagomorphs ( / ˈ l æ ɡ ə m ɔː r f / ) are
6020-414: The rest of the members are smaller and sterile, and function as workers. Some individuals are of intermediate size. They help with the rearing of the young and can take the place of a reproductive if one dies. The Damaraland mole rat is characterized by having a single reproductively active male and female in a colony where the remaining animals are not truly sterile, but become fertile only if they establish
6106-408: The rodents is their pairs of continuously growing, razor-sharp, open-rooted incisors . These incisors have thick layers of enamel on the front and little enamel on the back. Because they do not stop growing, the animal must continue to wear them down so that they do not reach and pierce the skull. As the incisors grind against each other, the softer dentine on the rear of the teeth wears away, leaving
6192-798: The scents of their neighbors and respond less aggressively to intrusions by them than to those made by non-territorial "floaters" or strangers. This is known as the " dear enemy effect ". Many rodent species, particularly those that are diurnal and social, have a wide range of alarm calls that are emitted when they perceive threats. There are both direct and indirect benefits of doing this. A potential predator may stop when it knows it has been detected, or an alarm call can allow conspecifics or related individuals to take evasive action. Several species, for example prairie dogs, have complex anti-predator alarm call systems. These species may have different calls for different predators (e.g. aerial predators or ground-based predators) and each call contains information about
6278-441: The sharp enamel edge shaped like the blade of a chisel . Most species have up to 22 teeth with no canines or anterior premolars . A gap, or diastema , occurs between the incisors and the cheek teeth in most species. This allows rodents to suck in their cheeks or lips to shield their mouth and throat from wood shavings and other inedible material, discarding this waste from the sides of their mouths. Chinchillas and guinea pigs have
6364-422: The species. The altricial state is typical for squirrels and mice, while the precocial state usually occurs in species like guinea pigs and porcupines. Females with altricial young typically build elaborate nests before they give birth and maintain them until their offspring are weaned . The female gives birth sitting or lying down and the young emerge in the direction she is facing. The newborns first venture out of
6450-607: The staple diet of many carnivorous species. Domestic rabbits can be litter box trained, and—assuming they are given sufficient room to run and a good diet—can live long lives as house pets. Lagomorphs are widespread around the world and inhabit every continent except Antarctica. However, they are not found in most of the southern cone of South America, in the West Indies, Indonesia or Madagascar, nor on many islands. Although they are not native to Australia, humans have introduced them there and they have successfully colonized many parts of
6536-639: The stomach contents of the North American white-footed mouse , normally considered to be herbivorous, showed 34% animal matter. More specialized carnivores include the shrewlike rats of the Philippines, which feed on insects and soft-bodied invertebrates, and the rakali or Australian water-rat, which devours aquatic insects, fish, crustaceans, mussels, snails, frogs, birds' eggs, and water birds. The grasshopper mouse from dry regions of North America feeds on insects, scorpions, and other small mice, and only
6622-536: The surface of the ground, but may have a burrow into which they can retreat. Beavers and muskrats are known for being semiaquatic, but the rodent best adapted for aquatic life is probably the earless water rat from New Guinea. Rodents have also thrived in human-created environments such as agricultural and urban areas . Though some species are common pests for humans, rodents also play important ecological roles. Some rodents are considered keystone species and ecosystem engineers in their respective habitats. In
6708-435: The surface to feed by seizing the roots of plants with its jaws and pulling them downwards into its burrow. It also practices coprophagy. The African pouched rat forages on the surface, gathering anything that might be edible into its capacious cheek pouches until its face bulges out sideways. It then returns to its burrow to sort through the material it has gathered and eats the nutritious items. Agouti species are one of
6794-484: The surplus in crevices and hollow trees. In desert regions, seeds are often available only for short periods. The kangaroo rat collects all it can find and stores them in larder chambers in its burrow. A strategy for dealing with seasonal plenty is to eat as much as possible and store the surplus nutrients as fat. Marmots do this, and may be 50% heavier in the autumn than in the spring. They rely on their fat reserves during their long winter hibernation . Beavers feed on
6880-443: The teeth from growing too long. In addition, all lagomorph teeth grow continuously, while for most rodents, only the incisors grow continuously. Lagomorph and rodent incisors are structured differently. Lagomorphs have more cheek teeth than rodents. Both have a large diastema . Lagomorphs are almost strictly herbivorous , unlike rodents, many of which will eat both meat and vegetable matter. Lagomorphs have no paw pads; instead,
6966-469: The ultraviolet (UV) spectrum and therefore can see light that humans can not. The functions of this UV sensitivity are not always clear. In degus , for example, the belly reflects more UV light than the back. Therefore, when a degu stands up on its hind legs, which it does when alarmed, it exposes its belly to other degus and ultraviolet vision may serve a purpose in communicating the alarm. When it stands on all fours, its low UV-reflectance back could help make
7052-474: The water surface or house mice rattle their tails to indicate alarm. Some species have vestigial tails or no tails at all. In some species, the tail is capable of regeneration if a part is broken off. Rodents generally have well-developed senses of smell , hearing, and vision. Nocturnal species often have enlarged eyes and some are sensitive to ultraviolet light. Many species have long, sensitive whiskers or vibrissae for touch or "whisking" . Whisker action
7138-459: The winter. They are solitary animals. Newborns are precocial (eyes and ears open, fully furred). Several litters are born during the year in a form (a nest above ground, usually under a bush). They are preyed upon by large mammalian carnivores and birds of prey. Rabbits, members of the Leporidae family (excluding Lepus (hares)) are generally much smaller than hares and include the rock hares and
7224-403: The year. These species tend to have large swings in population size. The gestation period of the pika is around one month long, and the newborns are altricial (eyes and ears closed, no fur). The social behaviour of the two groups also differs: the rock dwellers aggressively maintain scent-marked territories, while the burrowers live in family groups, they interact vocally with each other and defend
7310-461: Was more closely related to rodents (although not a direct ancestor). The leporids first appeared in the late Eocene and rapidly spread throughout the Northern Hemisphere; they show a trend towards increasingly long hind limbs as the modern leaping gait developed. The pikas appeared somewhat later in the Oligocene of eastern Asia. Lagomorphs were certainly more diverse in the past than in
7396-412: Was the first mammal for which seismic communication was documented. These fossorial rodents bang their head against the walls of their tunnels. This behavior was initially interpreted as part of their tunnel building behavior, but it was eventually realized that they generate temporally patterned seismic signals for long-distance communication with neighboring mole rats. Footdrumming is used widely as
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