Big ears are one of the secrets of its heat resistance, and it is like a big radiator. A study of 1992 shows that an African elephant weighing 2,000 kg can emit excess heat by flapping its ears at 20℃. However, some African elephants can weigh as much as 7,000 kilograms, and most of them live in an environment where the temperature is as high as 40℃. At the same time, the ears of Asian elephants are one-third the size of African elephants, so they can only radiate one-third of the heat through their ears. In this way, it is not enough to dissipate heat only by ears.
The Wiesenberger team at the Austrian Veterinary University also discovered another heat-resistant secret of elephants. They studied six African elephants in Vienna Zoo. When elephants open their mouths, they throw pills and other delicacies into their throats. In fact, "pills" are not wrapped in medicine, but in temperature sensors and radio transmitters. Through the "pill", the researchers obtained the thermal imaging of the elephant. The researchers found that when elephants radiate heat, hot spots appear in their ears, legs and abdomen. When a certain part of the body is covered with capillary network, a large amount of "hot blood" rushes here, which makes the skin warm, thus forming hot spots on the thermal imaging map. In other words, the place where hot spots appear is the heat dissipation area of the body.
All mammalian skin is like a radiator. Through the skin, animals can emit excess heat to regulate their body temperature. Elephants are the first known mammals that can open, close and fuse hot vents. According to Wiesenberger, this enables elephants to accurately regulate their body temperature in weather with suitable temperature. Elephants only use this strategy when they feel comfortable, neither cold nor hot. Some researchers have even concluded that elephants have the ability to cool an organ by cooling a certain skin.
Mammals have hair on their body surface, and the hair layer can maintain a thin layer of air on the skin surface, which can reduce heat loss and has the function of heat preservation. However, the elephant's hair is sparse and can't play this role. So, what is the function of the hard and vertical hair on the elephant's body surface?
Mayward of Princeton University in the United States found that the sparse hair of an elephant was not for heat insulation, but played a role as a "radiator". Elephant hair can improve the heat dissipation effect by 20%! He believes that elephant hair is not a legacy of evolution, and may have evolved the function of helping elephants cool down.
However, despite so many ways to dissipate heat, elephants may not be able to emit excess heat when they encounter extremely hot weather. Therefore, elephants have evolved another cooling strategy. Wiesenberger also made 17 Asian elephants in Germany and Thailand swallow "pills" and monitored the nuclear temperature of the elephants with temperature sensors. Experiments show that in Germany, when the temperature is 265438 0℃, the fluctuation range of the elephant's nuclear temperature is about 0.5℃. In Thailand, when the temperature is 30℃, the fluctuation range of the elephant's nuclear temperature exceeds 65438 0℃, from the lowest 35.5℃ at night to 38℃ during the day!
Asian elephants improve their resistance to daytime high temperature by lowering their body temperature at night.
It's like a power outage in summer. As long as you put a proper amount of ice cubes in the refrigerator, the food in the refrigerator will not deteriorate because the temperature in the refrigerator rises too fast, no matter how high it is during the day. This ability was once thought to be the patent of desert mammals. For example, camel's body temperature can rise from 34℃ at night to 4 1℃ during the day!
With the intensification of global warming, the tropical areas where African elephants live will become hotter. The temperature rise in these areas is greater at night than during the day, which will make it more difficult for large animals like African elephants to maintain proper body temperature, and the survival prospects of elephants are worrying. Scientists predict that under the "forced" environment, African elephants will inevitably change some behavior patterns and their bodies will change accordingly. Perhaps, African elephants will eventually "slim down" to adapt to the increasingly hot environment.
The original text is from Science Illustrated.
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