The Black Rat (Rattus rattus, also known as the Ship Rat, Roof Rat or House Rat) is a common long-tailed rodent of the genus Rattus and the subfamily murinae (Old World rodents). The species originated in tropical Asia and spread through the Near East in Roman times before reaching Europe in the 8th Century and spreading with Europeans across the world. Today it is again largely confined to warmer areas, having been supplanted by the Brown rat (Rattus norvegicus) in cooler regions.

Despite its name it comes in several colour forms. Compared to the Brown Rat, it is a poorer swimmer, but a better climber. It is usually black to light brown in colour with a lighter underside. A typical rat will be 20 cm long with a further 20 cm of tail. It is agile and climbs well, tending even to flee upwards. It is nocturnal and omnivorous, with a preference for grains although it spoils more than it consumes. In a suitable environment it will breed throughout the year, with a female producing three to six litters a year of up to twenty young. A rat can live for up to four years. Social groups of up to sixty can be formed.

It is a carrier of a number of diseases, of which bubonic plague, typhus, and trichinosis are the most well known.

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