Cricetids use vision, hearing, touch, smell, and taste to perceive the world. The relative importance of these senses varies among species and relates to each species' lifestyle. For example, fossorial species tend to have a reduced need for vision, and often have reduced eyes, but may have a keen tactile sense. Some cricetids produce (and therefore are likely to hear) sounds that surpass the range of human hearing (Smith 1972). Chemical signaling with pheromones and scent marks is an extremely important aspect of communication in this group, as these odors can quickly send a signal about the identity and status of an individual (Johnston 2003). In general, cricetids communicate using a combination of chemical, tactile, visual, and auditory cues--the relative importance of which varies among species.
Communication Channels: visual ; tactile ; acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; ultrasound ; chemical
About 21% of the species in this family are included on the IUCN's Red List of Threatened Species. Of these, 58 are lower risk, 2 are near threatened, 27 are vulnerable, 27 are endangered, 11 are critically endangered, and 10 are lacking sufficient data. Another 6 (Pemberton's deer mice, Peromyscus pembertoni, Antillean giant rice rats, Megalomys desmarestii, Santa Lucia giant rice rats, Megalomys luciae, Darwin's Galapagos mice, Nesoryzomys darwini, indefatigable Galapagos mice, Nesoryzomys indefessus, and Nelson's rice rats, Oryzomys nelsoni) have gone extinct in recent years. Human-induced habitat loss and degradation threaten most of these species. Also, many cricetids have restricted geographic ranges, making them even more vulnerable to extinction. Few actions, other than basic research, are underway to conserve these and other rodent species, as most attention is directed toward saving larger, more charismatic fauna.
Cricetidae is an extremely diverse family of muroid rodents. This is one of the largest families of mammals, with 681 species in 130 genera and 6 subfamilies. The subfamilies of Cricetidae are: Arvicolinae (lemmings, voles, and muskrat), Cricetinae (hamsters), Lophiomyinae (crested rat), Neotominae (North American rats and mice), Sigmodontinae (New World rats and mice), and Tylomyinae (vesper rats and climbing rats).
Some cricetids are vectors of human diseases, including hantavirus and lyme disease. Those that dwell in agricultural areas sometimes damage crops. Also, some species are considered nuisance animals when they enter homes, raid food stores, gnaw on household goods, and build nests in unwelcome places.
Negative Impacts: injures humans (carries human disease); crop pest; household pest
Some cricetid species, especially the hamsters, thrive in captivity and are popular pets. As research animals, cricetids have contributed greatly to the fields of ecology, physiology, and genetics. Some species are harvested for food or for their valuable fur. Also, cricetids play an important role in controlling populations of insect pests.
Positive Impacts: pet trade ; food ; body parts are source of valuable material; research and education; controls pest population
Cricetids are valuable members of many ecosystems, in which they fulfill roles as predators, prey, and dispersers of seeds and mycorrhizal fungi. Fossorial species turn over earth as they dig and therefore aerate the soil. Cricetids have a large impact on forest succession by preying on tree seedlings, and are sometimes considered keystone species when they play such roles (Manson et al. 2001). Their high reproductive output and regular boom and bust cycles in population numbers result in dramatic impacts on their plant prey species and predators that rely mainly on cricetid prey. Many types of parasites use cricetids as hosts, including species of ticks and mites, fleas, lice, bot flies, nematodes, and flukes (Kinsella 1991).
Ecosystem Impact: disperses seeds; soil aeration ; keystone species
Commensal/Parasitic Species:
Cricetids may be carnivores, omnivores, or herbivores. Food eaten by the group as a whole include leaves, pine needles, seeds, berries, fruits, roots, tubers, stems, twigs, nuts, fungi, insects, slugs, earthworms, aquatic crustaceans, spiders, small terrestrial vertebrates, and fish. Many cricetids are generalists that dine on many of these food items, while some are specialists that eat just one or two. Some cricetid species cache food for later use.
Foraging Behavior: stores or caches food
Primary Diet: carnivore (Eats terrestrial vertebrates, Piscivore , Eats eggs, Insectivore , Eats non-insect arthropods, Molluscivore , Scavenger ); herbivore (Folivore , Frugivore , Granivore , Lignivore); omnivore ; mycophage
Cricetids range throughout North America, South America, Europe, and most of Asia from southern China northwards.
Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native ); neotropical (Native )
Other Geographic Terms: holarctic
Cricetids occupy a broad spectrum of habitats. Their range encompasses dry, wet, warm and cold climates. Habitats utilized by cricetids include grasslands, meadows, agricultural fields, forests, rocky mountain landscapes, deserts, suburban yards, human habitations, beaches, lakes, ponds, streams, marshes, swamps, and bogs. They also span a range of elevations from sea level to over 5000 meters above sea level.
Habitat Regions: temperate ; tropical ; polar ; terrestrial
Terrestrial Biomes: tundra ; taiga ; desert or dune ; savanna or grassland ; chaparral ; forest ; rainforest ; scrub forest ; mountains
Aquatic Biomes: lakes and ponds; rivers and streams
Wetlands: marsh ; swamp ; bog
Other Habitat Features: urban ; suburban ; agricultural ; riparian
As is the case with most small muroid rodents, cricetids face vast array of predators and usually live less than a year in the wild. Lifespan in captivity is often much longer, up to a decade in some species.
Many cricetids are mouse-like or rat-like in appearance: they have small, somewhat elongated bodies, and are gray or brown with long tails, large eyes, and prominent ears and whiskers. However, body forms in this diverse group vary. Arvicolines, cricetines, and some sigmodontines have rounded bodies, with short tails, small eyes, and ears that are almost completely hidden in the fur. Pelage colors in this family include nearly every shade of brown and gray, including light golden brown, dark russet, and black. There is a tendency for the undersides to be paler, and many species have white bellies and chins. Pelage color may vary within cricetid species, as well, with two or more color morphs found in some populations. The texture of the fur ranges from silky and soft to coarse and spiny. Tails may be tufted, well-furred, or nearly naked. Cricetids are small (pygmy mice of the genus Baiomys weigh up to 8 grams) to large (muskrats, Ondatra zibethicus, weigh almost 2 kg) relative to other rodents. Sexual dimorphism varies across species: in some cases, males are larger than females, and in other cases, females are larger than males. Some species do not exhibit sexual dimorphism at all. There are various specializations for different lifestyles found in this group; for example, the long, powerful claws of long-clawed mole mice (Geoxus) are adapted for digging, whereas the partially webbed hind feet and rudder-like tails of muskrats are adapted for swimming.
The cricetid dental formula is usually 1/1, 0/0, 0/0, 3/3 = 16.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry ; polymorphic
Sexual Dimorphism: sexes alike; female larger; male larger
Cricetids are preyed upon by a variety of mammalian carnivores (such as foxes, cats, and weasels), birds of prey (such as hawks, eagles, and owls) and snakes.
In order to avoid easy detection by predators, many cricetids are nocturnal. Their neutral-colored coats tend to blend in with the surroundings and afford some degree of camouflage. When alarmed, they seek refuge in trees, burrows, or other places where the predator cannot follow. As a last resort, cricetids often bite their attacker with their sharp incisors and utter high-pitched chirps. One unique cricetid species, Lophiomys imhausi, bears aposematic white and black patches, exudes a musky odor, and has erectile, stiff hairs that may mimic porcupines.
Known Predators:
Anti-predator Adaptations: mimic; aposematic ; cryptic
Some cricetid species are monogamous, living in small family groups consisting of a mated pair and their offspring. Juveniles of some arvicoline species help in raising their younger siblings. Many, perhaps the majority, are polygynous or promiscuous, having many different mates throughout the year with whom they associate for only brief periods of time.
Mating System: monogamous ; polygynous ; polygynandrous (promiscuous) ; cooperative breeder
Cricetid reproduction is characterized by large litters and short interbirth intervals. Most cricetids are able to breed when they are just a few months old. Female cricetids often have a postpartum estrus and mate shortly after giving birth (although sometimes implantation is delayed until the female stops lactating). In some species, ovulation is induced by the act of mating. Seasonality of reproduction varies with climate; cricetids in warm, constant climates are likely to breed year round, whereas those in variable climates are more likely to only breed at favorable times of the year (although even those that live in unfavorable climates have been known to breed year round, even bearing litters beneath the snow). Under ideal conditions (such as those in the laboratory), cricetids have been known to produce more than 12 litters per year.
Key Reproductive Features: iteroparous ; seasonal breeding ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; induced ovulation ; fertilization (Internal ); viviparous ; delayed implantation ; post-partum estrous
Female cricetids often build nests in which they raise their offspring, which range from altricial to precocial. Like all mammals, they provide their young with milk until the young are able to eat solid food. Male parental care, including grooming, carrying, and huddling, exists in some species and has been shown to enhance survival of the young (Gubernick and Teferi 2000). Time to independence is usually short, and juveniles of many species disperse and breed on their own the same year they are born.
Parental Investment: altricial ; precocial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Male, Female); pre-independence (Provisioning: Female, Protecting: Male, Female)
The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, muskrats, and New World rats and mice. At almost 608 species, it is the second-largest family of mammals, and has members throughout the Americas, Europe and Asia.
The cricetids are small mammals, ranging from just 5–8 cm (2.0–3.1 in) in length and 7 g (0.25 oz) in weight in the New World pygmy mouse up to 41–62 cm (16–24 in) and 1.1 kg (2.4 lb) in the muskrat. The length of their tails varies greatly in relation to their bodies, and they may be either furred or sparsely haired. The fur of most species is brownish in colour, often with a white underbelly, but many other patterns exist, especially in the cricetine and arvicoline subfamilies.
Like the Old World mice, cricetids are adapted to a wide range of habitats, from the high Arctic to tropical rainforests and hot deserts. Some are arboreal, with long balancing tails and other adaptations for climbing, while others are semiaquatic, with webbed feet and small external ears. Yet others are burrowing animals, or ground-dwellers.[1]
Their diets are similarly variable, with herbivorous, omnivorous, and insectivorous species all being known. They all have large, gnawing, incisors separated from grinding molar teeth by a gap, or diastema. Molar teeth may be bunodont like in cricetines or lophodont like in arvicolines or some new world mice. Although a few exceptions occur, the dental formula for the great majority of cricetids is:
Cricetids' populations can increase rapidly in times of plenty, due to a combination of short gestation periods between 15 and 50 days, and large litter sizes relative to many other mammals. The young are typically born blind, hairless, and helpless.[1]
The cricetids first evolved in the Old World during the Early Oligocene.[2][3] They soon adapted to a wide range of habitats, and spread throughout the world. The voles and lemmings arose later, during the Pliocene, and rapidly diversified during the Pleistocene.[4]
The circumscription of Cricetidae has gone through several permutations. Some members of the family as currently defined have been placed in the family Muridae. Some muroids have historically been placed in Cricetidae, such as mouse-like hamsters (subfamily Calomyscinae, family Calomyscidae), gerbils (subfamily Gerbillinae, family Muridae), the crested rat (subfamily Lophiomyinae, family Muridae), zokors (subfamily Myospalacinae, family Spalacidae), the white-tailed rat (subfamily Mystromyinae, family Nesomyidae), and spiny dormice (subfamily Platacanthomyinae, family Platacanthomyidae). Multigene DNA sequence studies have shown the subfamilies listed below to form a monophyletic group (that is, they share a common ancestor more recently than with any other group), and other groups now considered muroids should not be included in the Cricetidae.[5]
The cricetids thus currently include one fossil and five extant subfamilies, with about 112 living genera and 580 species:
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The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, muskrats, and New World rats and mice. At almost 608 species, it is the second-largest family of mammals, and has members throughout the Americas, Europe and Asia.
