Which animal has the largest ears? You would possibly think, it is the elephant and you would be right, sort of.
As the largest living land animal, the African elephant have the largest ears of any living animal, consistent with Mary Ellen Holden, a zoologist & mammalogist at American Museum of Natural History in New York City.
But the creature with the largest ears relative-to the size of its body is the long-eared jerboa (Euchoreutes naso), a nocturnal, insect eating rodent that lives in the deserts of China & Mongolia.
The long-eared jerboa (rhymes with Samoa) measures about 4 inches (10 centimeters) from head-to-rump (not counting its long tail). Its ears, measuring 1.5 to 2 inches (3.8 – 5 cm) long, are 40 percent to 50 percent the length of its body.
“It has the longest ears relative-to its body size in the entire animal kingdom,” Holden said.
For comparison, ears of the African elephant average around 4 feet (1.2 m) in length, consistent with Holden, but that is just 17% of their body length, which averages nearly 20 to 25 feet (6 to 7.5 m).
In 2007, the long-eared jerboa, which has been rarely seen on camera, made the news with a video taken during a Zoological Society of London trip to the Gobi Desert in Mongolia.
The critter is “a bit like the Mickey Mouse of the desert,” expedition leader & conservation biologist Jonathan Baillie said, consistent with the video description.
Why such big ears? Large ears help the long-eared jerboa & other mammals living in hot, dry environments get rid of excess heat.
“African elephants, fennec foxes, long-eared jerboas, they’re able to thermoregulate by having rapid heat loss through the very highly vascularized ears,” Holden said.
These animal’s ears are large & thin and they house many small blood vessels, she said. While circulating through the ears, blood releases heat into the air, thereby helping the animal cool-off.
When the animal is hot, blood vessels in its ears expand to release even more heat, Holden said. At night or whenever it is cold, the animals’ blood vessels constrict to help to keep them warm.
“I think most people agree that large ears are generally correlated with warmer environments,” Holden said.
“And if you look at African & Asian elephants, African elephant ears are much larger than Asian elephant ears because African elephants inhabit a hotter climate.”
Asian elephants’ ears, measuring nearly 1.6 feet (0.5 m) long, make-up only about 8 percent of their body length. As far as heat dissipation strategies go, using ears to cool-off is a good adaptation to desert life.
It serves-as an alternative to sweating, allowing desert creatures to conserve water in an environment, where that resource is scarce, consistent with Holden.
Large ears can also help the long-eared jerboa detect the low-frequency sounds coming-from its insect prey & its predators, Holden said.