Why the elephant could be the largest land mammal.

ElephantWhen searching for the limit to body size, researchers began to look at how pachyderms manage their temperature levels. The skin of these animals is not as insensitive as one might think. One of the functions of the furless skin, with its good blood circulation, is to disperse heat, which is important for large animals given their limited heat exchange capacity.

With the help of infra-red thermography, it was possible to see that not only the ears (the elephant’s large ears function as heat exchangers), but also «thermal windows» on the rest of the body are used to balance the animal’s temperature. Because the animals do not sweat or pant, there remained the question as to how accumulated heat is dispersed. The infra-red camera only measures the surface temperature, not the core temperature.

Elephant infraredTo solve this issue, researchers at the Zoology Department of Vienna University developed sophisticated capsules to be swallowed, which were fed to the elephants and recorded the animal’s internal temperature during their passage through the intestine. The capsules were fitted with a signal so that they could be found after they had been passed by the animal.

The effort was worth it: for the first time it was possible to show that elephants can cope with internal temperature fluctuations; hitherto this was known only of camels which can only do so when the outside temperature is hotter than that of their body and no drinking water is available.

The dogma of “The larger the animal, the more stable the temperature” is wrong with elephants anyway: Similar to the daily variation of outdoor temperature elephants save during the day the heat (even if it is less than 35 degrees), leave up to 37 degrees in the body, and give it out the heat at night when it is cool, and cool to 35.5 degrees off. This is an enormous thing for such a big animal. This trick could possibly explain why are elephants so large.