Notice that the ears are cooler — an elephant uses its ears for thermoregulation. The same idea as fins on any heat sink: lots of surface area. That’s necessary because of the elephant’s shape (the spherical approximation is much more reasonable for an elephant than for a cow) meaning has a small surface-to-volume ratio, so it’s efficient at retaining heat.

With a wide surface area of outer ear tissue, hot blood in the arteries is cooled as it is filtered through the vast network of capillaries and veins. Thus, the body temperature is regulated with the cooled blood returning to the main body.