Water is an amazing molecule. The oxygen atom pulls on its two hydrogens in a way that creates a slightly-negative side and a slightly-positive side. Like opposite poles of a magnet sticking together, the molecule’s charges mean it can stick to other water molecules and even other surfaces.
Water can seem to defy gravity through a property known as capillary action. You can easily experiment with capillary action with a paper towel: dip a corner of the towel in a glass of water and watch the water creep upwards on its own. The water molecules use their charge to cling to the narrow gaps in the towel and pull other water molecules up with them.
What could this water chemistry have to do with reptiles? The Thorny Devil lizard of Australia can essentially drink through its feet – a fascinating example of capillary action in use. The lizard’s rough skin has narrow passages that allow water to climb from a puddle, up the lizard’s legs, and toward its eyes and mouth. Watch this video to see the skin changing color as the water travels, just like water moving up a paper towel.
Biologists think that some snakes also use capillary action to drink. Folds of tissue inside their mouth may form tiny tubes where water moves passively into their mouth. It doesn’t happen very often, so I felt lucky this week to catch Emory the rat snake taking a drink. It was hard to tell if she was using capillary action, but it was neat to watch!