The giant South American river turtle, credit Brian HorneEver since I learned that butterflies drink turtle tears, my mind has held onto the image of turtles crying. What are they so sad about? Well, it might have to do with their lifestyle. Marine turtles in particular have a fairly bleak life trajectory—they drag themselves out of the sea, lay somewhere around 100 eggs on the beach at dusk, and then head back to the water. And the most of those baby turtles die, eaten before they hatch, picked off by predators as they cross the sand, or gulped down once they hit the water. However, a new study shows that one species of marine turtles in Brazil maintain contact with their babies, and even communicate with them.
A Giant South American river turtle hatchling emerges from its shell. Credit: C. Ferrara/Wildlife Conservation SocietyTwo scientists of the Instituto Nacional de Pesquisas de Amazonia published their findings in BioOne, documenting the behavior of female Giant South American River turtles, as well as the sounds they make. Like whales and dolphins, turtles use the water to carry their sounds, which would otherwise be inaudible.
But this is just the tip of the iceberg. The researchers documented different sounds for different behaviors, identifying five in total. There’s migration, gathering at the egg-laying beaches, laying the eggs, waiting in the water after laying egg, and the wait for the babies to hatch. The researchers concluded that the turtles communicate throughout the entire process, and that their communications help organize the groups of female turtles and synchronize their behavior.
Giant South American river turtles’ nests. Credit: Camila FerraraThe researchers documented adult female turtles waiting for their babies to emerge from the eggs, and then helping maneuver them into safe places with plentiful food. Such learning is nature’s own means of self-preservation, so while many turtle species are in trouble, perhaps the actions of well-intentioned biologists have actually done more harm than good.
It’s possible that when try to intervene to help boost turtle populations, scientists may be interrupting inter-turtle communications, throwing off the turtles’ patterns. Maybe human intervention isn’t as helpful as the watchful eyes (and clucking tongues) of the adult turtles, which is probably a good point to remember. It’s unclear if or how damaging the interruption of the turtles’ survival-oriented social behavior is, but these findings may change the tactics biologists use to help save and boost turtle populations, and perhaps other endangered populations as well.
