Rats
Key
Features of Rats
Rats are various medium sized rodents. "True rats" are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, and the brown rat, R. norvegicus. Many members of other rodent genera and families are also called rats and share many characteristics with true rats.
Biology
Rats are distinguished from mice by their size; rats generally have bodies longer than 12 cm (5 inches).
Distribution
By most standards, rats are considered pests or vermin. They can be very destructive to crops and property. Rats can quickly overpopulate when they live in a place where they have no predators, such as in certain cities, and their numbers can become hard to contain.
Rats have a significant impact on food production. Estimates vary, but it is likely that about one-fifth of the world's total food output is eaten, spoiled or destroyed by rats. It is interesting to note that about one-third of the food purchased by humans is thrown away as rubbish in certain areas.
Significance
Rats can carry over thirty different diseases dangerous to humans, including Weil's disease, typhus, salmonella and bubonic plague.
