Several years ago, we learned that female Caecilians (odd, legless amphibians) of some species grow extra layers of skin with which to feed their young. This unbelievable feeding strategy was first documented on film in the BBC series Life in Cold Blood, and is among the most fascinating (if chilling!) footage I’ve ever seen. Tadpoles of the recently discovered Fringe-Limbed Treefrogs, Ecnomiohyla rabborum are now known to feed upon living skin as well. In this case, it is the male parent that provides dinner with its own body – the only frog, and the only male amphibian, known to do so.
Discovery of a New Species
The Fringe-Limbed Treefrog is known only from a single mountainous rainforest in Coclé, central Panama. It was first collected in 2005, and was described as a new species in 2008. Its species name, rabborum, was given in honor of noted herpetologists Mary and George Rabb.
An Unusual Degree of Parental Care
Females deposit 60-200 eggs in pools of water located in tree hollows above ground. The tadpoles are large, and in time their body mass may exceed the volume of water held in the cavity. Perhaps this is why such an unusual feeding strategy has developed, as any food contained in the water must surely be consumed in short order.
In any event, male Fringe-Limbed Treefrogs remain with the tadpoles and have been seen to periodically back into the cavity. Further observations revealed that the tadpoles were foraging on their parent’s skin. The details of this unexpected discovery are not known and, as you will see below, may never be.
In another unusual twist on frog reproduction, male Fringe-Limbed Treefrogs appear to guard their tree hollows even outside of the breeding season. This would seem to make good sense, as water-filled tree cavities are likely a rare resource, but territoriality of this kind is not well-documented in amphibians.
Barely Studied but near Extinction
Unfortunately, Chytrid fungus (Batrachochytrium dendrobatidis), which is devastating amphibian populations the world over, swept through the frog’s habitat in 2006. The Fringe-Limbed Treefrog was last heard calling in 2007, but has not been seen since. Only 2 males, both in institutions in the USA, are known to exist.
The fact that this most unusual frog may be consigned to extinction before being fully studied underlies the crisis situation in which amphibians and amphibian biologists find themselves today. The Fringe-Limbed Treefrog is classified as Critically Endangered by the IUCN, but its disappearance may be in sight if a new population is not discovered.
Fringes for Gliding and Spines for Mating
As if skin-feeding tadpoles were not enough to distinguish the Fringe-Limbed Treefrog, this canopy-dwelling oddball has several other unique traits. Assisted by expansive webbing between the toes and skin fringes that line the forearms and feet (please see photo of related species), it escapes enemies by gliding through the air in the manner of several other related and unrelated species (please see drawing). Individuals have been observed to soar over 30 feet to the ground without ill effect.
Males are also equipped with spine-studded forearms, perhaps to better grasp slippery mates high above the forest floor.
Zoo Atlanta Fact Sheet and Photo (this zoo is home to 1 of the 2 known specimens)
A photo of this amazing frog and further information may be found in the March, 2011 issue of Herpetological Review (V42, N1).