The western Amazon is lower in sodium than many places on Earth, because it is more than 1,000 miles (1,600 kilometers) from the Atlantic Ocean, a prime source of salt, and is cut off from windblown mineral particles to the west by the Andes Mountains. Dust and minerals make their way into the Amazon from the east, sometimes all the way from north Africa. But much of this material is removed from the air by rain before it reaches the western Amazon, said Phil Torres, a conservation biologist who does much of his research at the Tambopata Research Center in Peru.
Unlike butterflies, turtles get plenty of sodium through their carnivorous diet. Meat contains significant levels of the salt, Torres told LiveScience. But herbivores sometimes struggle to get enough sodium and other minerals, he added. "They end up needing this extra mineral source," he said.
Turtle tears are not the only source of such salts for butterflies; the insects also readily get the salt from animal urine, muddy river banks, puddles, sweaty clothes and sweating people, said Geoff Gallice, a graduate student of entomology at the Florida Museum of Natural History, who has witnessed butterflies flocking to turtle tears in the western Amazon rain forest. Here butterflies are witnessed "puddling," gathering minerals from mud.
One question that arises: Does the butterfly feeding help, hurt or have no impact on the turtles? Torres said it's not completely clear, but the teary endeavor probably has little impact on the turtles, other than perhaps making them more vulnerable to predators like big cats, since the butterflies can obstruct their vision.
In fact, the turtles — blinded and drowning in butterfly kisses — are sometimes easier to photograph than unadorned animals, which may be able to spot an approaching photographer more easily. The photos were taken by Jeff Cremer, marketing director for Rainforest Expeditions, an ecotourism company that hosts guests in the Peruvian Amazon and organizes trips to the jungle.
More from LiveScience
Douglas has written for the New York Times Green Blog, Popular Mechanics and Discover Magazine. He has an M.A. in journalism from the Science, Health & Environmental Reporting Program at New York University. Before that he studied biology and English literature at Washington University in St. Louis. To find out what his latest project is, you can follow Douglas on Google+.