The lack of salt in the western (Peruvian) Amazon has led many of the animals there to go to unusual lengths to asdd it to their diets. While monkeys and Macaws have resorted to eating dirt and licking clay for the mineral deposits, butterflies have come up with their own method by literally drinking tears shed by turtles.
In fact, “the sight of butterflies flocking onto the heads of yellow-spotted river turtles in the western Amazon rain forest is quite common,”noted Phil Torres, of the Tambopata Research Center in Peru, as well as being affiliated with Rice Univeristy. He also wondered whether the butterflies might also be drinking in amino acids from the tears.
"Potentially, they could be getting other resources out of those eyeballs that we don't even know about," he stated."Basically, we have to go start swabbing turtle eyeballs and see what we get."
Regardless, the butterflies don’t seem to be doing any harm to the reptiles, which get their own salt from the meat they eat.
"The turtles have enough tears to feed the butterflies simply because the butterflies are taking so little," observed Geoff Gallice, a graduate student of entomology at the Florida Museum of Natural History."They simply uptake salts through a process similar to absorption by placing the proboscis on the salt-laden [tears] and passively 'feed.'"
Gallice, also added that “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.” However, the phenomena of feeding on the tears seems to be unique to the region, and hasn’t been see anywhere else.