In order to get their dose of sodium, butterflies in the Amazon rainforest turn to crying turtles. Scientist Phil Torres points out that while turtles get plenty of salt from their carnivorous diet, butterflies (and most herbivores) have a harder time finding the important mineral, especially in the west Amazon rainforest where there is very little salt at all. Their solution lies, in part, in the damp edges of turtle eyes. Torres wants to study the behavior more to find out if there are other minerals in the moisture that the insects are after.
"Potentially, they could be getting other resources out of those eyeballs that we don't even know about," Torres told Live Science. "Basically, we have to go start swabbing turtle eyeballs and see what we get."
According to Live Science, "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, you can see bees engaging in the same behavior: