No Exit

This is a photo of the inside of a leatherback sea turtle’s mouth.

Their esophagus is lined with papillae: sharp, keratinized spikes that enable the turtle to dine on jellyfish without them slipping out when they expel the seawater they swallow along with it.

These papillae also protect the leatherback from the stinging cells of the jellyfish.

As with most prey, the prey they feed on don’t go down without a fight, so this adaptation is a necessity.