In Brazil, a flea toad, scientifically known as Brachycephalus pulex, has been discovered and may be the world’s smallest vertebrate. This tiny amphibian was first described by scientists in 2011 and is smaller than the previous record holder for the world’s smallest vertebrate. Despite its small size, only a limited number of flea toad specimens have been collected from its habitat on forested hilltops in southern Bahia, Brazil.
To verify the species’ maturity and sex, the gonads of the frogs were examined. It was found that only males have vocal slits. Adult male B. pulex frogs are slightly over 7 millimeters long, smaller than females, making them smaller than the previously known smallest amphibian, the Paedophryne amauensis frog from Papua New Guinea. The findings have led experts to believe that the flea toad may be the smallest extant frog in the world.
The study also highlighted how small the flea toads can get compared to other mini frogs, with the smallest specimen in the study being only 6.45 millimeters long. At such small scales, frogs tend to develop unusual anatomical quirks, such as losing toes or having underdeveloped ears.
Researchers also suggested that there may be even smaller vertebrates yet to be discovered, leading to the possibility of the next record-holder being another small frog or perhaps a parasitic male of a deep-sea anglerfish.