The Yucatecan Casque-headed Frog is a good example of where old sayings sometimes fall short. The old adage goes “if it looks like a duck and sounds like a duck, its a duck“. But this is a case where an animal that looks and sounds like a duck….is actually a frog!
These strange duck-billed tree frogs are restricted to the Yucatan Peninsula, where they are quite common during the rainy season. They can be found on roads and trails at night and their calls can be heard from any wooded area. They are conspicuously absent during most of the year because they “aestivate” (the summer version of “hibernate”) in dried mud, emerging when it is time to breed.
Their bizarre head ornamentation (“casque”) is actually composed of bony shelves and ridges of the skull which are fused to the cranial skin. They not only have a duck-like beak, but there is a bony ridge coming forward from each eye towards the mid-line of the skull. The function of this bony ornamentation is unknown but it has been hypothesized that these frogs use these bony plants to block their burrow entrances during periods of inactivity.