"Mice" redirects here. For other uses, see Mice (disambiguation).
This article is about the animal. For the computer input device, see Mouse (computing). For other uses, see Mouse (disambiguation).
A mouse (plural: mice) is a small rodent characteristically having a pointed snout, small rounded ears, a body-length scaly tail and a high breeding
rate. The best known mouse species is the common house mouse (Mus musculus). It is also a popular pet. In some places, certain kinds of field mice
are locally common. They are known to invade homes for food and shelter.
Domestic mice sold as pets often differ substantially in size from the common house mouse. This is attributable both to breeding and to different
conditions in the wild. The most well known strain, the white lab mouse, has more uniform traits that are appropriate to its use in research.
The American white-footed mouse (Peromyscus leucopus) and the deer mouse (Peromyscus maniculatus), as well as other common species of
mouse-like rodents around the world, also sometimes live in houses. These, however, are in other genera.
Cats, wild dogs, foxes, birds of prey, snakes and even certain kinds of arthropods have been known to prey heavily upon mice. Nevertheless, because
of its remarkable adaptability to almost any environment, the mouse is one of the most successful mammalian genera living on Earth today.
Mice can at times be vermin, damaging and eating crops, causing structural damage and spreading diseases through their parasites and feces. In
North America, breathing dust that has come in contact with mouse excrement has been linked to hantavirus, which may lead to Hantavirus
Pulmonary Syndrome (HPS).
Primarily nocturnal animals, mice compensate for their poor eyesight with a keen sense of hearing, and rely especially on their sense of smell to
locate food and avoid predators.
Mice build intricate burrows in the wild. These burrows typically have long entrances and are equipped with escape tunnels/routes. In at least one
species, the architectural design of a burrow is a genetic trait.
Breeding onset is at about 50 days of age in both females and males, although females may have their first estrus at 25–40 days. Mice are
polyestrous and breed year round; ovulation is spontaneous. The duration of the estrous cycle is 4–5 days and estrus itself lasts about 12 hours,
occurring in the evening. Vaginal smears are useful in timed matings to determine the stage of the estrous cycle. Mating is usually nocturnal and may
be confirmed by the presence of a copulatory plug in the vagina up to 24 hours post-copulation. The presence of sperm on a vaginal smear is also a
reliable indicator of mating.
Female mice housed together tend to go into anestrus and do not cycle. If exposed to a male mouse or the pheromones of a male mouse, most of the
females will go into estrus in about 72 hours. This synchronization of the estrous cycle is known as the Whitten effect. The exposure of a recently
bred mouse to the pheromones of a strange male mouse may prevent implantation (or pseudopregnancy), a phenomenon known as the Bruce effect.
The average gestation period is 20 days. A fertile postpartum estrus occurs 14–24 hours following parturition, and simultaneous lactation and
gestation prolongs gestation 3–10 days owing to delayed implantation. The average litter size is 10–12 during optimum production, but is highly straindependent. As a general rule, inbred mice tend to have longer gestation periods and smaller litters than outbred and hybrid mice. The young are called
pups and weigh 0.5–1.5 g (0.018–0.053 oz) at birth, are hairless, and have closed eyelids and ears. Cannibalism is uncommon, but females should not
be disturbed during parturition and for at least 2 days postpartum. Pups are weaned at 3 weeks of age; weaning weight is 10–12 g (0.35–0.42 oz). If
the postpartum estrus is not utilized, the female resumes cycling 2–5 days post-weaning.
Newborn male mice are distinguished from newborn females by noting the greater anogenital distance and larger genital papilla in the male. This is
best accomplished by lifting the tails of littermates and comparing perineums.
Main article: Laboratory mouse
Mice are common experimental animals in laboratory research of biology and psychology fields primarily because they are mammals, and also
because they share a high degree of homology with humans. They are the most commonly used mammalian model organism, more common than rats.
The mouse genome has been sequenced, and virtually all mouse genes have human homologs. They can also be manipulated in ways that are illegal
with humans, although animal rights activitsts often object. A knockout mouse is a genetically engineered mouse that has had one or more of its
genes made inoperable through a gene knockout.
Reasons for common selection of mice are small size, inexpensive, widely varied diet, easily maintained, and can reproduce quickly. Several
generations of mice can be observed in a relatively short period of time. Mice are generally very docile if raised from birth and given sufficient human
contact. However, certain strains have been known to be quite temperamental. Mice and rats have the same organs in the same places, with the
difference of size.
All members of the Mus genus are referred to as mice. However, the term mouse can also be applied to species outside of this genus. Mouse often
refers to any small muroid rodent, while rat refers to larger muroid rodents. Therefore, these terms are not taxonomically specific. For simplicity,
only the rodent subgenera belonging to the Mus genus are listed here.
Genus Mus - Typical mice
Subgenus Coelomys (East Asia)
Subgenus Mus (Eurasia to North Africa, except for the house mouse which is worldwide.)
Subgenus Nannomys (Sub-Saharan Africa)