The eggs of the Darwin’s frog of South America, Rhinoderma darwinii are laid in the moist ground.

The male parent sits on guard until there is a sign of life in them.

The father then swallows the eggs and keeps them in his croaking sac of the throat.

The eggs remain thus protected until they hatch.

The frog lets out the young ones to go on and live their own lives.

How do these frogs know that they should not eat their own young ones and

protect them so well but for all the others they are good tasty food?