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Elephants can’t handle the heat

Elephants don’t have floppy sun hats, battery-powered misting fans or ice-cold popsicles to help keep them cool on a hot day. The animals have a lot of mass compared with their skin’s surface area and can’t get rid of much heat through the skin. Instead, they store that heat in their bodies.

So how hot is too hot for a 9,000-pound pachyderm? Biologist Michael Rowe kept a close eye on the temperatures of two Asian elephants, named Panya and Jean, while they exercised. Keepers at the Audubon Zoo in New Orleans walked the elephants around a half-mile track in weather ranging from 55 degrees to 87 degrees, while Rowe monitored their internal and external temperatures. On hot days, the elephants’ sun-drenched skin was above their body temperature, preventing any heat from radiating away. The gigantic animals held on to about 100 percent of the heat generated by exercise, Rowe reported May 1 in the Journal of Experimental Biology. Rowe projected that a mere 4 hours of walking in the heat of a summer day could be fatal to elephants. The animals avoid overheating by resting during the day, cooling off in water or shifting their activity to nighttime.

ScienceNOW is the online daily news service of the journal Science.