Why Do Rabbits Have Such Big Ears? 0 8

The long ears of rabbits serve not only for excellent hearing but also function as radiators for cooling. To avoid predators, rabbits need to move frequently and quickly, so they require an efficient "cooling device."

If they relied solely on sweating to shed excess heat, it would require significant amounts of water. Cooling through heat exchange allows them to survive in arid conditions and when food is limited, such as tree bark. Under the skin of these animals are large blood vessels (those who have petted rabbits have surely noticed this), the diameter of which can vary significantly.

When a rabbit needs to get rid of heat, the ear arteries work at full capacity, and when energy needs to be conserved, their lumen narrows almost to complete closure. The hotter the climate, the more heat the body needs to dissipate, which is why the most "eared" rabbits live in the south. The length of their ears can reach half the length of their body.

This "latitudinal gradient" is observed not only in rabbits but also in other mammals, and it pertains not only to ears. In biology, this phenomenon is known as Allen's rule.