How do egg-eating snakes break open swallowed eggs?

Specialized egg-eating snakes (genus Dasypeltis and Elachistodon westermanni) possess unique anatomical adaptations to consume bird eggs. Because their mouths are enormously distensible and their teeth are greatly reduced, they can swallow eggs as large as a chicken's whole.12

Once the egg is swallowed, it is broken open by ventral spines located on the neck vertebrae that extend into the esophagus. These spines puncture or crush the shell, allowing the snake to squeeze the contents out. Once the liquid contents have been consumed, the snake regurgitates the crushed shell.1