Rat
From Wikinfo
[[sv:R�tta]]
Rattus rattus
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A rat is a small omnivorous rodent of the genus Rattus. Rats are mammals somewhat bigger than their relatives the mice, but seldom weighing over 300 grams.
Well-known species of rat are the Brown Rat, Rattus norvegicus; the Black Rat, Rattus rattus; the Rice Rat, Rattus argentiventer, and the Indian Mole Rat, Bandicota bengalensis.
These four common varieties of rat often live with and near humans, share their food and spread disease. The Black Plague is believed to have been spread by rat-borne parasites. Rats are also blamed for damaging food supplies and other goods. They have a very poor reputation; "rat" is an insult and "to rat on someone" is to betray them by denouncing a crime or misdeed they committed to the authorities.
Nevertheless, many people keep rats as pets; some fanciers have developed exotic varieties and colours of rat. Rats are also used as experimental specimens, sometimes being bred for that purpose.
Many other species of rat exist, including the wood or pack rats, the Polynesian Rat and a number of species loosely called kangaroo rats.
The rat (or mouse) is also one of the 12-year cycle of animals which appear in the Chinese zodiac related to the Chinese calendar. It is thought that each animal is associated with certain personality traits.
Rats might eat each other in stressful environments or when the number of rats in a space is very high, but cannibalism to prevent diseases from spreading is normal, where dead rats are eaten before they start spreading diseases.
Rats in the Laboratory
Like mice, rats are frequently the subjects of medical, psychological and other biological experiments. This is because they grow quickly to sexual maturity and they are easy to keep and to breed in captivity. Scientists have bred many "lines" of rats specifically for experimentation. Generally, these lines are not transgenic, however. The easy techniques of genetic transformation that work in mice do not work for rats.
Further Reading
- The Story of Rats: Their Impact on Us, and Our Impact on Them, S. Anthony Barnett, Allen & Unwin, Crows Nest, NSW, Australia, 2002, trade paperback, 202 pages, ISBN 1-86508-519-7. Monograph by an experienced "rat" man. Nice bibliography.
- Robert Sullivan, Rats: Observations on the History and Habitat of the City's Most Unwanted Inhabitants, St. Martins Press, April, 2004, hardcover, 256 pages, ISBN 1582343853
References
- Adapted from the Wikipedia article, "Rat" http://www.wikipedia.org/wiki/Rat July 25, 2003
