rat

Rats are medium-sized rodents belonging to the genus Rattus, in the family Muridae. The term typically refers to several species, most notably the brown rat (Rattus norvegicus) and the black rat (Rattus rattus). The genus contains more than 50 species, many with overlapping ranges across continents.

Physically, rats have a slender body, long tail, and large incisors that grow continuously. Fur coloration ranges from grayish-brown to black. Adult size varies by species, with body lengths roughly 15 to 25 cm and tails of similar length; weights range from about 150 to 500 g in common pest species.

Rats are omnivorous and opportunistic feeders. They are primarily nocturnal and highly social, living in colonies with complex hierarchies. Reproduction is rapid: gestation lasts about 21 to 23 days, with litter sizes typically 6 to 14 young and multiple litters per year. In the wild, lifespans are often one to two years; longer in captivity.

Distribution and habitat: native to parts of Asia, rats have colonized every continent except Antarctica, frequently thriving in urban and agricultural settings. The brown rat is an adept climber and swimmer, commonly found in sewers and buildings; the black rat favors warmer climates and higher elevations.

Ecological and public health importance: rats can cause property damage, contaminate food, and act as reservoirs or vectors for various pathogens affecting humans and livestock. Control relies on sanitation, exclusion, trapping, and judicious use of rodenticides within an integrated pest-management framework.

Rats are also important in scientific research, serving as model organisms in physiology, genetics, and medicine due to their biological similarities to humans and practical advantages for laboratory study. Their interactions with humans have shaped urban ecosystems for centuries.