Do you know how alligators get around the water soooo quietly when stalking prey?
They move their lungs! Instead of moving their arms or legs, alligators can move their lungs to subtly change their position in the water. If they were to move anything else, they'd make a lot of unnecessary noise!
(Peek-a-Boo, I see you)
To move their lungs, they use their diaphragm, pelvic and abdominal muscles. This changes their balance in the water and makes their lungs move.
This allows them to dive, surface and roll over super quietly!