Inaddition to a rib cage, the aspir

In
addition to a rib cage, the aspiration pump in the crocodile uses
back-and-forth movements of the liver like a piston to act on the
lungs. During inhalation, the rib cage expands and the liver is
pulled back while the crocodile aspirates fresh air into its lungs.
During exhalation, the rib cage and forward-moving liver
compress the lungs and the crocodile expels spent air.