Lips of the mole rat keep dirt out of their mouth while excavating by puckering closed behind the protruding front teeth.

“Gnawing one’s way through earth could clearly be a distasteful business, but the mole-rat avoids mouthfuls of soil with a technique used by many other gnawers. It puckers its lips behind those extravagantly protruding teeth and so keeps its mouth tight shut while its teeth busily excavate.” (Attenborough 1979:254)

Last Updated August 18, 2016