KCET 2014 Biology Solved Paper

Allen’s rule states that some extremities (mainly arms, legs,ears, and snout or nose) of animals are comparatively shorter in the cooler parts of the world than in the warmer regions. Large extremities provide more surface area without much increase in volume, for example, long ear lobes of desert fox. The heat loss will be more, if the surface area is large. So, to prevent heat loss, the extremeties of animals living in colder regions are shorter.