Mouse

This article is about the rodent. For the computing input device, see Mouse (computing). For other uses of the word mouse, see Mouse (disambiguation).

Mouse Temporal range: Late Miocene - Recent434
File:Mus Musculus-huismuis.jpg
House mouse, Mus musculus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Rodentia
Superfamily:	Muroidea
Family:	Muridae
Subfamily:	Murinae
Genus:	Mus Linnaeus, 1758

Feral mouse

A mouse (plural mice) is a small animal that belongs to one of numerous species of rodents. The best known mouse species is the common house mouse (Mus musculus). It is found in nearly all countries and, as the laboratory mouse, serves as an model organism in biology. It is also a popular pet. The American white-footed mouse (Peromyscus leucopus) and the deer mouse (Peromyscus maniculatus) also sometimes live in houses. These species of mice live commensally with humans.

Although mice may live up to two years in the lab, the average mouse in the wild lives only about 5 months, primarily due to heavy predation. Cats, wild dogs, foxes, birds of prey, snakes and even certain kinds of insects have been known to prey heavily upon mice. Nevertheless, due to its remarkable adaptability to almost any environment, and its ability to live commensally with humans, the mouse is regarded to be the third most successful mammalian species living on Earth today, after humans and the rat.

Mice can be harmful pests, damaging and eating crops and spreading diseases through their parasites and feces. In western North America, breathing dust that has come in contact with mouse feces has been linked to the deadly hantavirus. The original motivation for the domestication of cats is thought to have been for their predation of mice and their relatives, the rats.

History

Mice have been known to humans since antiquity. The Romans differentiated poorly between mice and rats, calling rats Mus Maximus (big mouse) and referring to mice as Mus Minimus (little mouse). In Spanish similar terms are in use: ratón for mouse and rata for rat.

Discoloration in mice was supposedly first noticed in China by 1100 BC, where a white mouse was discovered. However, there is sufficient evidence to believe that white mice were first noticed before that.

The word "mouse" and the word muscle are related. Muscle stems from musculus meaning small mouse - possibly because of a similarity in shape. The word "mouse" is a cognate of Sanskrit mus meaning 'to steal,' which is also cognate with mys in Old Greek and mus in Latin.

Characteristics

Mice range in size from 3 to 14 inches (8 to 35 cm) long (including a long tail). They weigh from 1/4 to 2 ounces (7 to 57 gm). The coat color ranges from white to brown to gray. Most mice have a pointed snout with long whiskers, round ears, and thin tails. Many mice scurry along the ground, but some can hop or jump.

Distribution and Habitat

All species of Mus are native to Eurasia and Africa, where they range from lowlands to mountaintops. The five species in the subgenus Pyromys are found in Sri Lanka, India, and mainland Southeast Asia. Much of their range originally consisted of open grasslands or grassy patches in forests. Shortridge's mouse (M. shortridgei).

Diet

The mouse is an omnivore; it will eat almost anything. It eats grain, seeds, grasses, fruit, roots, stems, and small animals like worms, grasshoppers (and other insects), arachnids, etc.

Behavior

Mice are timid, social, and territorial. They are usually active in the night time, while others, such as the harvest mouse, are active both day and night.

Reproduction

Baby mice just a day old

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 due to delayed implantation. The average litter size is 10-12 during optimum production, but is highly strain dependent. 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 grams 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 grams. If the postpartum estrus is not utilized, the female resumes cycling 2-5 days postweaning.

Newborn male mice are distinguished from newborn females by noting the greater anogenital distance and larger genial papilla in the male. This is best accomplished by lifting the tails of litter mates and comparing perineums.

Laboratory mice

Knockout mice

Mice are common experimental animals in biology and psychology primarily because they are mammals, and so 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 would be considered unethical to do with humans (note Animal Rights). A knockout mouse is a genetically engineered mouse that has had one or more of its genes made inoperable through a gene knockout.

There are other reasons for why mice is used in laboratory research. Mice are small, inexpensive, 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, just different proportions.

There are hundreds of established inbred, outbred, and transgenic strains. In the United States, mice are not protected by the Animal Welfare Act (AWA) (administered by the United States Department of Agriculture (USDA), APHIS). However, the Public Health Service Act (PHS) administered by the National Institutes of Health (NIH) does cover their treatment.

As pets

Main article: Fancy mouse

Mice have gained popularity as pets. Many people buy mice as companion pets. They can be playful, loving and will get used to being handled, and run to you. Some common mouse care products are:

• Cage - Usually a hamster or gerbil cage, but special mouse cages are now available. You can also use a small aquarium (5 gallons for up to 3 mice, 10 gallons for 8 or so mice) with a mesh top, so there is no risk of them escaping. But this is not recommended, as the lack of proper ventilation can cause respiratory complications in mice.
• Food - Special pelleted and seed-based food is available. Mice can generally eat most rodent food (for rats, mice, hamsters, gerbils, etc)
• Bedding - Usually made of hardwood pulp, such as aspen, sometimes from shredded, uninked paper or recycled virgin wood pulp. Cedar or pine should not be used because they contain harmful liquids that can damage any rodent's respiratory system. Corn cob bedding should not be used because it promotes Aspergillis fungus, can grow mold once it gets wet and is rough on their feet. There should be at least 2 inches of bedding to allow the mice to dig and burrow. You may also use shredded paper and/or shredded tissues.

Pet mice

Some benefits of having mice as pets are

• Minimal shedding and allergens
• Entertaining and affectionate
• Inexpensive
• Clean (contrary to popular belief)
• Socially self-sufficient when in a group of other mice
• Significantly less likely to bite than other rodent pets
• Quite intelligent given their size
• Fun
• Loving

Disadvantages include:

• Small and quite fragile (not as easy to handle as a dog or a cat)
• Defecate and urinate frequently
• Nocturnal
• Frequent eye infections when under stress
• Easily subject to disease when without optimal care
• Frequent reproduction
• Short lifespan
• Prone to many other diseases

Nutrition

Mice should be fed a commercial pelleted mouse diet and water ad lib. These diets are nutritionally complete, but they still need a large amount of varied vegetables. Food intake is approximately 15g/100g BW/day; water intake is approximately 15 ml/100g BW/day.

As food

"Pinkie" mice for sale as reptile food.

Humans have eaten mice since prehistoric times. They are still eaten as a delicacy throughout eastern Zambia and northern Malawi, where they are an excellent seasonal source of protein.[1] In most other countries, mice are no longer routinely consumed by humans. Some people are very afraid of mice, which is normal. Across the US petowners keep exotic pets such as snakes, lizards, frogs, tarantulas, and birds of prey. Most US pet stores now carry mice for this purpose. Because they breed quickly, grow quickly, are easy to care for, and can be sold in a wide variety of sizes, this makes them suitable for consumption by animals of various sizes. Mice also seem to be a desirable food item for a very large variety of carnivores. Common terms used to refer to different age/size mice are pinkies, fuzzies, hoppers, and adults. Pinkies are newborn mice that have not yet grown fur; fuzzies have some fur but are not very mobile; hoppers have a full coat of hair and are fully mobile but are smaller than adult mice. These terms also refer to the various growth stages of rats (also see Fancy rat).

More Information About Mice As Pets

Mice should not be left outside as there are many predators such as birds. Watch them at all times when outside. Mice are partially smelly, more so the males than females, so it would be wiser to buy a female when choosing, although more expensive at times. If you look after your pet carefully and well you'll have the perfect pet.

Popular Culture

• In the book and film of the same name; "The Hitchikers Guide to the Galaxy", mice are said to be the most intelligent beings on earth and that they commissioned the building of earth and now own it.
• Walt Disney's most well-known characters such as Mickey and Minnie are mice.
• In The Green Mile, Mr. Jingles was a mouse.
• In the movie Never Cry Wolf, the Farley Mowat character survives on a diet of mice while investigating the lives of Arctic wolves.

See also

• Audiograms in mammals
• House mouse
• Mouse trap
• Mice in fiction
• Musophobia (fear of mice)
• Vacanti mouse

External links

• Fancy Mice 'A complete resource for pet owners and show breeders'
• Mice as pets
• Impact of mice on endangered species
• High-resolution images of cross section of mice brains
• History of the mouse (with focus on their use in genetics studies)