If this fanged cutie looks full, it has probably just eaten another frog CT scan revealing Odontobatrachus natator‘s deadly fangs

Zoologger is our weekly column highlighting extraordinary animals – and occasionally other organisms – from around the world

Species: Odontobatrachus natator

Habitat: fast-flowing rivers and waterfalls in hilly regions of west Africa

Any lingering notion that frogs are cute little animals that are only a threat to flies must surely be laid to rest. The Emei moustache toad has a weaponised moustache, used to gore rivals, and one African species can break its own toe bones to make claws.


To this intimidating list we now add a sabre-toothed frog. This beast is equipped with a pair of powerful fangs, and gets at least some of its food by munching on other frogs.

It sounds like an oddity, and the latest evidence suggests that it really is. This fanged frog belongs to a previously unknown family of frogs, genetically different from all others. Nowadays such discoveries are extremely rare.

A frog alone

Odontobatrachus natator is a “torrent frog”, so called because it lives in fast-flowing streams. There are several groups of torrent frogs from around the world, so Michael Barej at the Leibniz Institute for Research on Evolution and Biodiversity in Berlin, Germany, and his colleagues tried to sort out which family this fanged frog belonged to.

The team collected wild frogs and used molecular markers to “barcode” the species, allowing them to assess its genetic relationship to other animals. To their surprise, the fanged frog showed no close relationship to any other frog family. They estimated that its family split from other frogs some 100 million years ago, when dinosaurs dominated the planet.

“A molecular clock approach revealed the last common ancestor to be present in the Cretaceous,” says Barej. It means that O. natator belongs to a novel family of frogs.

Discovering a new species of animal is a dream for most biologists, and finding a new genus – the category above species – is more than most can hope for. But to spot a new family, the classification higher still, is rare indeed. It would be like discovering cats, which all belong to the family Felidae. You really had to be a Victorian naturalist to have a good chance of describing a family. “By far the largest number of family descriptions go back to the 19th century,” says Barej.

However, frogs are an exception to this rule. “With recent advances in molecular biology and genetic techniques, the amphibian tree of life has been shaken up and reordered quite a bit,” says Cameron Hudson of the University of Sydney in Australia.

Fang you very much

And so to the monstrous fangs. They are about a millimetre long, and are the only teeth in this sabre-toothed frog’s lower jaw. The upper jaw, by contrast, is covered with many small teeth.

To find out what the fangs are for, Barej looked in the stomach of a single specimen. He found another frog. It may be that the fangs are used in hunting, but as nobody has seen O. natator eat another frog, nobody knows for sure.

“The shape of the teeth and the finding of a frog in the stomach shows that they are at least opportunistic frog eaters,” Barej says. But it is not yet known whether frogs are O. natator‘s main prey, or just an occasional treat.

Frog-on-frog predation is not unheard of. “It is common in large species, says Hudson. “It either takes the form of cannibalism of juveniles, or predation on smaller species. Frogs are typically gape-limited predators, so they often will try to eat anything that is small enough to fit in their mouth.”

And to think, lots of people are scared of spiders.

Journal reference: Frontiers in Zoology, DOI: 10.1186/1742-9994-11-8