The Goliath frog (Conraua goliath) of Africa is the biggest frog in the world. It can weigh over 3 kg (7 pounds) and grow to the size of an American football. It can also leap 3 meters (almost 10 feet) in a single jump.
On the other end of the frog size spectrum is a newly described frog species from the Atlantic rainforest of Brazil. It fits easily on a fingertip. Meet Brachycephalus dacnis:
At a length of 6.95 millimeters (0.27 inches), B. dacnis is smaller than a pencil eraser! This teeny frog has given scientists a new appreciation of just how small vertebrates can get. The only known frog smaller than B. dacnis was found in February 2024 in northeastern Brazil and beats it by just 0.5 mm (0.02 in).
Researchers formally described the species in late October 2024 after encountering it in the Atlantic Forest in southeastern Brazil’s São Paulo state.
Frogs in the tiny Brachycephalus genus are notorious for their clumsy landings. They often tumble over or fall on their heads after jumping! The reason many Brachycephalus frogs are clumsy is that their vestibular system–a part of the inner ear that helps maintain balance–is small in size.
But B. dacnis is a great jumper that can jump an impressive 32 times its own size! B. dacnis seems to have retained its inner ear structure, allowing it to hear and leap quite well compared to its frog cousins.
“The size makes this frog very special,” said Edelcio Muscat, one of the researchers who described B. dacnis. “The miniaturization process hasn’t affected any of its organs or its skeleton.”
In 2016, Edelcio Muscat was on a typical nighttime expedition, carefully turning over leaves on the forest floor, when one of the frogs jumped out. Recordings of its croak are more similar to a cricket’s chirp than to a typical frog’s ribbit. These recordings would confirm it was a unique species years later.
Brazil is home to the world’s largest number of amphibian species. Many of these species live in the Atlantic Forest, an area of high biodiversity that includes Brazil’s largest cities, São Paulo and Rio de Janeiro. Dozens of species are described from the Atlantic Forest every year, but only 13% of the original Atlantic Forest remains.
“The discovery shows us how much we need to preserve the Atlantic Forest,” Muscat said. “There are still species it supports that we have not yet found.”
David Brown adapted this story for Mongabay Kids. It is based on an article by Shanna Hanbury, published on news.mongabay.com:
