Amazonian butterflies drink salty turtle tears

Scott Sutherland

Researchers working in the western Amazon rain forest have been seeing a strange sight — turtles with their faces completely covered by butterflies that are jockeying for position to drink the turtles' tears. The reason for this? The tears are a much-needed source of sodium for the insects.

The region of the Amazon that these turtles and butterflies live in, in eastern Peru, is an area that has a very low amount of sodium. Any salt carried inland by winds from the Pacific Ocean is usually deposited on the western slopes of the Andes. Any that comes from the Atlantic Ocean is usually lost due to rain long before it reaches this remote area. As a result, insects and animals that don't specifically get sodium from their diet need to be more imaginative about where they get the essential mineral.

Turtles eat a variety of different things, but they get their sodium from the meat they eat. A butterfly's diet consists mostly of drinking nectar (not something known for its sodium content), so they need to get their sodium from someplace else.

According to Phil Torres, a researcher at the Tambopata Research Center in Peru, who posted about the butterflies' strange but necessary behaviour on his blog, says that they'll get it from wherever they can — even the sweat on your skin and clothes. "I'd even bet that if you laid out on one of those logs with your skin covered and your eyes open, you may get lucky enough and eventually have a swarm of colorful butterflies imbibing on your tears, too," he said.

If you happen to recognize Torres' name (I did), that's because he's one of the researchers who discovered the spiders who build decoys in their webs.

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Butterflies aren't the only insects that use turtles as a sodium drip. Bees in the area do the same thing, and they're apparently a lot more annoying than the butterflies:

(Photo courtesy: Jeff Cremer/perunature.com)

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