A rat's bare tail works as a radiator for shedding heat
That naked, scaly-looking tail puts many people off rats, but it is a precision tool. Thin skin laced with blood vessels lets it dump body heat far faster than the belly can, and its muscles and many vertebrae help the animal sense its position while climbing.
Rat is a loose everyday label, not a scientific category. Broadly, a large muroid rodent gets called a rat and a small one a mouse. Pack rats and kangaroo rats carry the name without belonging to the true rats of the genus Rattus, whose best-known members, the black rat and the brown rat, both came from Asia. Those two split from other Old World rats in Asian forests at the start of the Pleistocene. Wild rats rarely exceed 500 grams, and there are 56 known species.
Studies of exercising rats show the tail loses heat much more efficiently than the abdomen, thanks to its rich blood supply and high ratio of surface to volume. It also works as a sensory aid, with dense muscle and connective tissue helping orient the animal in three dimensions. In an emergency, the outer skin of the tail can slip off in a predator's grip, an escape trick called degloving that comes at a cost to the animal.
Rats live on every continent people inhabit except Antarctica. The common species are commensals, thriving beside humans and causing heavy food losses, especially in poorer countries. Yet those pests are a minority. Many rat species are island specialists, and several are endangered by habitat loss or competition from the spreading brown, black and Polynesian rats.
They mature fast, able to breed at six weeks though not socially mature until five or six months, and many wild rats survive only about a year because so much eats them. Rats can carry pathogens such as Leptospira and Toxoplasma. The Black Death is traditionally blamed on Yersinia pestis spread by fleas riding black rats through medieval European cities. Vocabulary buffs will enjoy the terms: males are bucks, mothers are dams, babies are kittens or pups, and a group is a mischief.
Source: Rat
