The Unken Reflex

This morning I saw something that I had never seen before, a common frog exhibiting the unken reflex. The unken reflex (unken is the German for toad) is a defensive posture adopted by several amphibian groups, including salamanders, toads, and some frogs.

The unken reflex is elicited when an individual feels endangered by a predator. The frog contorts its body and raises its legs above its head and back to reveal previously hidden brightly coloured patches on the inner limb or the belly. The exposed colours serve as a warning to a predator that the frog they are about to eat may be poisonous.The frog remains rigidly immobile whilst in unken reflex. In fact the common frog is not very poisonous but it is probably taking advantage by mimicking the common toad whose parotid glands do contain a very evil cocktail of toxins.

As far as I can ascertain this behaviour has only rarely been observed in the European frog Rana temporaria and so I am feeling very chuffed and privileged!