Crocodiles and alligators are the epitome of stealth. They can wait motionlessly for prey on the surface of the water, dive to the bottom, or roll around the length of their bodies, all without creating a single ripple.

This sneaky manoeuvrability is all the more impressive for the fact that a crocodilian can pull it off without moving its legs or tail. It’s particularly difficult because a waiting crocodilian has to move slowly and methodically, and must make do without the helpful forces of lift and drag that accompany faster movements.

Now, for the first time, we know how they do it. They use their lungs like floats, and shift them about their torso using four sets of muscles. If the