Lateral undulation is a snake's only way of moving in water, and the most common way of moving altogether. In this mode, the body of the snake alternately bends to the left and right, resulting in a series of rearward-moving "waves". While this movement appears rapid, snakes have rarely been seen moving faster than two body-lengths per second, often much less. This mode of movement has the same amount of calories burned per meter moved as running in lizards of the same mass.