Rats are medium Seltene Meerschweinchenrassen. True rats belong to the genus Rattus and the one very popular among humans is the black rat Rattus rattus. Many members of other genera and families of rodents are also referred to as rats as they share a number of features similar to that of true rats. They are different from mice and should be confused with them. Rats are large muroid rodents while mice are small muroid rodents. Muroid family is a very complex family and the terms rat and mice are not taxonomically relevant.
The best known species are the Black rat Rattus rattus and the Brown rat Rattus norvegicus. These species are commonly known as Old World rats or true rats and they originated in Asia. They are bigger than Old World mice which weigh hardly 500 grams. The term rat is also used for some small animals which are not true rodents for example, kangaroo rats, bandicoot rats and North American pack rats. They are also rodents but do not belong to the genus Rattus. Males are known as bucks, unmated females are called as does and the pregnant females are known as dams. The young ones are known as kitten or pups. A group of rats is often termed as pack or mischief. In some developed countries the domesticated rat species are kept as pets in houses. R. norvegicus is commonly kept as pet and it originated in China and spread to Europe and eventually in the New World. Pet brown rats are also known as fancy rats.
The common species act as commensals as they live human surroundings. Such cause tremendous damage of the stored food products. Many species of brown and black rats have become endangered due to loss of natural habitats. Wild rats are known to be carriers of a number of pathogens and parasites like Toxoplasma gondii. Many species act as vectors of the Rat flea and are responsible for the spread of plague and other related diseases. Their average life span varies from 2-5 years. Specially bred species are kept as pets since the 19th century. Species commonly used as pet are Brown rat, Black rats and Giant pouched rats. Pet species do not cause any sort of harm to other pet animals like cats and dogs.
Brown rats are often used as model organisms in scientific research. With the publication of Rat Genome Sequence Brown Rat has become a very useful genetic tool. Domestic species differ from wild ones in a number of ways. They are calm and hardly bite and are able to tolerate crowding to a greater extent. Their brain, adrenal glands and heart, kidneys, liver are smaller than the wild rats. Rats are consumed as food by humans and sometimes eaten in emergency conditions also. Bandicoot rodents are the famous foods of some Southeast Asian areas. Their meat is a good source of protein. Rice field rats are traditionally consumed as food in the rice producing regions like Philipppines, Thailand and Combodia. They can also serve as vectors of a number of pathogens that cause disease like Lassa fever and Hantavirus. Rattus rattus and the rat flea Xenopsylla cheopis are very notorious for their eminent role in the transmission of bubonic plague.
They have a special role in both culture and religion. In India it is considered as the vehicle of Lord Ganesh. Their statue is always found in the Ganesh temple. In the Chinese culture it is first of the twelve animals of Chinese zodiac. European association with rats is strongly negative. Rats are used as substitute for vulgar interjections in the English Language. They have been hated as they act as vectors for a number of disease causing agents and have dirty habits. They have been used as experimental animals since time immemorial. One of the famous stories about rats is The Pied Piper of Hamelin in which a rat catcher saved the city from rats with the magical tune of his flute. The genus Rattus at present contains 64 species.
