This is a colorful example of how odd behaviors can evolve in the face of a limiting resource. In the Amazon, salt is a much sought-after commodity as it is generally lacking in the environment.
Turtle tears? A prime source of salt, and many butterfly species have adapted by perching on their face and sipping from the source. Although this is generally a common sight along the river, this image taken by our photo tour guide Jeff Cremer is the most adorably smothered I have seen, yet.
The turtles are basking in the sun to collect heat and energy for the day, and the butterflies find them by flying along the river. The turtles are ectothermic, so require heat energy from the environment to warm up their bodies and get active for the day. Bees also feed on turtle eyes, which seem to really bother the turtles, but they don’t appear to mind having butterflies drink from them as much.
While some people have said that the turtle gets an eye cleaning in exchange, I’m don’t think that is very likely. More likely is that this relationship is a form of commensalism, in which the butterfly benefits from the turtle, and the turtle isn’t really affected either way.
Butterflies in this area will do anything for salt- including drinking from your sweaty skin or backpack. 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.
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