Mouse. 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. 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. Species of mice are mostly classified in Rodentia, and are present throughout the order. Typical mice are classified in the genus Mus. Mice are typically distinguished from rats by their size. Generally, when someone discovers a smaller muroid rodent, its common name includes the term mouse, while if it is larger, the name includes the term rat. Common terms rat and mouse are not taxonomically specific. Scientifically, the term mouse is not confined to members of Mus for example, but includes such as the deer mouse, Peromyscus. 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 best-known strain, the white lab mouse, has more uniform traits that are appropriate to its use in research. 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, in certain contexts, can be considered vermin which are a major source of crop damage, 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. 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 long intricate burrows in the wild. These typically have long entrances and are equipped with escape tunnels or routes. In at least one species, the architectural design of a burrow is a genetic trait. 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. The mouse has approximately 2.7 billion base pairs and 20 pairs of chromosomes.They can also be manipulated in ways that are illegal with humans, although animal rights activists often object. A knockout mouse is a genetically modified mouse that has had one or more of its genes made inoperable through a gene knockout. Reasons for common selection of mice are that they are small and inexpensive, have a widely varied diet, are easily maintained, and can reproduce quickly. Several generations of mice can be observed in a relatively short 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. Main article: Fancy mouse Many people buy mice as companion pets. They can be playful, loving and can grow used to being handled. Like pet rats, pet mice should not be left unsupervised outside as they have many natural predators, including birds, snakes, lizards, cats, and dogs. Male mice tend to have a stronger odor than the females. However, mice are careful groomers and as pets they never need bathing. Well looked-after mice can make ideal pets.