Butterflies are drawn to turtle tears because the liquid drops contain salt, especially sodium, an essential element that is scarce in the western Amazon.
Because butterflies are so delicate, they don’t appear to damage the turtles in any way, however, they do make it harder for the turtles to see. This is an example of commensalism, which occurs when two species interact and one benefits while the other is unharmed but receives no benefit.
According to a recent study, crocodile tears also might be used to fulfill the needs of butterflies and bees. Similar to butterflies drinking turtle tears, these insects are believed to rely on crocodile tears for salt.