SCIENTISTS DECLARE THE BRAZILIAN FLEA TOAD THE SMALLEST VERTEBRATE IN THE WORLD
Is there an animal you could picture comfortably perching on your fingernail? The Brazilian flea toad is an actual animal, despite its sounding fictional. But don't let the name deceive you. It's a frog and not a flea or a toad. Its size leads some to believe it to be the world's smallest vertebrate and amphibian. Furthermore, although researchers have been aware of it for more than ten years, they have only lately been able to measure the species comprehensively. Researchers Wendy H. Bolaños, Iuri Ribeiro Dias, and Mirco Solé shared their findings in a paper published in the journal Zooloigica Scripta in February 2024.
Brachycephalus pulex, also known as the Brazilian flea toad, is indigenous to the forested hilltops of southern Bahia, Brazil's coast. The average length of a male frog is 7.1 millimetres (0.28 in), while the average length of a female frog, which is typically larger, is approximately 8.15 millimetres (0.32 in). The smallest person measured for the study had a length of 6.45 millimetres (0.25 in). With an average length of roughly 8 millimetres (0.31 in), the male Paedophryne amanuensis frogs from Papua New Guinea had previously been the smallest known vertebrate.
The Brazilian flea toad was first brought to the attention of herpetologist Mirco Solé in 2011. He was the first to examine the size of this species, but at the time the sample was too small to draw any firm conclusions. In 2024, Solé conducted a study with Wendy Bolaños and Iuri Ribeiro Dias from the Universidade Estadual de Santa Cruz, which provides more evidence that the Brazilian flea toad might be the tiniest vertebrate ever discovered. By measuring the gonads, or reproductive organs, of 24 male and 22 female flea toads, the researchers were able to determine their sex and whether or not they were adults.
The Brazilian flea toad and other small frogs differ significantly from their larger counterparts despite their similar sizes. For instance, they only have two toes on their feet as opposed to the normal five. Even though they can jump fairly well, some small frogs have unusually shaped inner ear tubes, which affects their balance and makes it more difficult for them to perform their trademark hopping.