Surviving under the ice

At first glance, this picture -- which I took at the edge of a pond -- may appear as nothing more than a few leaves and a stick.

Look closer, and you can see the leaves and the twig are lying upon or are partially in ice. A round brown object is beneath the ice.

It was difficult at first to see, but when the object moved I could tell it was a common snapping turtle. I inched down the pond bank for a closer photo.

The turtle saw me through the ice and, keeping to the bottom, slowly moved away. As it did, a baseball-sized bubble was released; it floated up and rested against the ice. I watched as the turtle raised its head up and put its nose into the bubble, where it kept it for a few minutes.

Could it be snapping turtles use bubbles under ice to breathe and survive when ice covers their watery refuge? It appears so, because this turtle was not hibernating.