Rats come in a number of colors and sizes, with 56 species alone in the genus Rattus, which contains the “true rats.” In addition, a number of animals which are not in this genus are referred to as rats, such as the naked mole rat, bandicoot rats, and pack rats, also called wood rats. The incredible diversity reflected in the number of types of rats illustrates the importance of the niche which these animals fit into. Many rat species are very unique, found only in isolated regions of the world.
Many rat species are named for the regions in which they are found, including Mentawi, Nillu, Bonthain, and Dusky Field Rats. These types of rats may not be well known to most people, since they live on small islands and in remote areas of the world. The two most famous types of rats are probably brown rats and black rats. The black rat is also known as a roof rat, ship's rat, or house rats. Black rats are very good climbers, and they are very clever animals, able to worm their way into extremely small spaces. Black rats can be found all over the world, thanks to their skill at stowing away on boats. They are especially infamous with humans because they are known carriers of the plague.
Brown rats, also called Norwegian, common, or wharf rats, are also very widely distributed around the world. Most rats kept as pets are brown rats, selectively bred to become “fancy rats” in an array of colors. Fancy rats are also bred to be fairly even-tempered, although they retain the traits of agility and curiosity associated with their wild cousins. Brown rats are also used extensively in scientific research.
Rats have been maligned throughout history because many types of rats carry diseases which are harmful to people. Rats have also been known to spoil food by urinating or defecating in it, and many people associate the presence of rats with uncleanliness and untidy habits. Health inspectors especially are known for not being fans of rats in the facilities they examine, despite the fact that rats are almost an unavoidable occurrence in urban areas.
Despite their negative associations, rats are actually very interesting, sensitive animals. Numerous types of rats display amazing levels of intelligence and problem solving skills, for example, and they often have a complex social structure. Rats also appear to be among the few animals which laugh to express joy, although the laugh of a rat is not audible to humans. Many pet rats form strong emotional bonds with their carers, and people who keep rats say that they are very loyal, friendly animals.