Hibernating Turtles Are Still Aware of What’s Going on Around Them

When temperatures dip below about 50 degrees, aquatic turtles like red-eared sliders take to the pond, where they will spend the next two or three months submerged and hibernating. They partially embed themselves in the pond mud, then wait as their body temperature drops. As they become colder, their heart rate slows to as little as one beat every couple of minutes. In this state, they don’t need to breathe. They turn off energy-taxing brain functions and seem completely out of it. Researchers assumed they entered a coma-like condition of complete disfunction and lack of awareness.

Now, however, new findings challenge that notion. Turtles turn out to be pretty in tune to what’s going on around them. As ScienceNOW reports, researchers performed two experiments on the turtles to test their awareness. First, the researchers anesthetized the turtles and inserted electrodes into their heads. When they deprived those turtles of oxygen or made conditions extremely cold, they found that the animals still registered neuronal responses to light.

In a second experiment, they locked turtles in a cold, dark watery chamber for two weeks, tricking the animals into thinking it was winter. When the turtles began to hibernate, however, the researchers began to mess with them, flipping on the lights, adding more oxygen to the tank, vibrating the water or warming things up. The light and warmth, they found, provoked immediate responses, whereas the vibration and oxygen did not, ScienceNOW reports.

“Hibernating turtles are not comatose, but remain vigilant during overwintering,” the scientists concluded in their paper. This way, as soon as the first signs of spring arrive, they can shake off those winter chills and paddle back into reptilian action.

More from Smithsonian.com:

The Decline of the Pig-Nosed Turtle
Unborn Turtles Actively Regulate Their Own Temperatures

Rachel Nuwer | | READ MORE

Rachel Nuwer is a freelance science writer based in Brooklyn.