Of all vertebrates, gray foam-nest tree frogs exhibit the most extreme form ... whips it to a foam with her back legs, and puts in her eggs. At this point, says Byrne, up to 20 more males ...

To protect their eggs, bubbling secretions from their bodies allow tree frogs to make characteristic “foam nests.” Usually ...

The eggs incubate here ... rinse off the worst of the slippery foam! Nonetheless, after such a successful and comprehensive performance the tree frog nest duly delivered a clutch of new tadpoles ...