Turtle Tears a Tasty Treat
By Amy O'Donnell
Seeing a colorful flock of butterflies perched on the head of a turtle is an unusual sight. What draws these lovely insects to their reptilian roost? A sip of turtle tears.
A Search for Sodium
In the rain forest surrounding the western Amazon, sodium is in short supply. This area has less available sodium than other areas of the Earth because the Atlantic Ocean is more than 1000 miles to the east and the Andes Mountains block windblown mineral particles from the Pacific Ocean to the west. This environmental scarcity may have inspired a remarkable behavior. Butterflies, and bees as well, have been observed drinking the tears from the eyes of yellow-spotted river turtles. According to Phil Torres, a researcher at the Tambopata Research Center in Peru, the insects probably use the tears as a source of salt.
Carnivores, such as the turtles, are able to get the sodium that they need from the meat in their diets. However, herbivores like butterflies and bees may have a more difficult time getting all of the salt they need. Researchers agree that the need for sodium may be a reasonable explanation for the butterflies' behavior. Some turtle species are known to excrete excess salt through their tears. Additionally, macaws in the western Amazon are known to lick clay, perhaps as a source of sodium and other minerals. The drinking of turtle tears has not been observed often outside of the western Amazon. Torres plans to study the phenomenon further to see if the butterflies are getting additional minerals or even amino acids from the tears.
What About the Turtles?
Does the butterflies' behavior have any negative impact on the turtles? The drinking itself probably does not hurt the turtles. The butterflies do not take much from the turtles, as they uptake salts by placing the proboscis in the tears and passively absorbing the minerals. However, the flocks of butterflies crowding around a turtles'eyes may interfere with their ability to see the approach of large predators. Many animals exhibit behaviors that allow them to survive in extreme conditions. Butterflies in the western Amazon demonstrate that a few tears may be a necessary part of life.
- What are other examples of animal adaptations to environmental scarcity?
- How would you describe the relationship between the butterflies and the turtles?