Why do rats have long tails?
ANSWER 1: Rats use their tails to balance and also to help maintain body temperature. The rat has specialised blood vessels, which control the amount of blood flowing to its tail. Blood flowing into the furless skin of the tail carries heat, which is then radiated out of the body. The rat can direct anywhere between 0.1 and 10 per cent of its cardiac output to the tail. Under ideal conditions, it can get rid of up to 20 per cent of its metabolic heat in this way. Conversely, restricting blood flow to the tail reduces heat loss in cold weather. It is interesting to note that the length of the rat’s tail is partly determined by the temperature of the environment in which it is raised. Radiating heat through the skin plays a major part in regulating body temperature in humans as well. ANSWER 2: Observing three rats suggests that the long tail usually around the same length as the body is used for balancing. Although rats cannot grasp objects with their tails, they do seem able to control
