A tiny amphibian, no larger than a coin, has been discovered in Brazil and may be the smallest vertebrate in the world. The flea frog, scientifically known as Brachicephalus pulek, was found sitting on a 27mm diameter Brazilian real coin.
Scientists first described this small creature in 2011 and found it to be smaller than the previous record holder for the world’s smallest vertebrate. Despite its small size, only a limited number of specimens of the flea frog have been collected from its habitat on the wooded hilltops of southern Bahia, Brazil.
To determine the maturity and sex of the species, scientists examined the gonads of the frogs. Only males were found to have vocal slits. Adult male flea frogs are just over 7 millimeters long, making them smaller than females. This makes them smaller than the smallest amphibian previously known, the Paedophrine amauensis frog from Papua New Guinea.
The study also highlighted how small flea frogs can be compared to other mini frogs, with some specimens measuring just 6.45 millimeters long. On such a small scale, these creatures tend to develop unusual anatomical quirks such as missing toes or underdeveloped ears.
Researchers suggest that there may be even smaller vertebrates yet to be discovered and raise the possibility that the next record-holder could be another small frog or perhaps a parasitic male deep-sea halibut.