‘Osteocephalus oophagus’ in French Guiana. Image: Mélissa Peignier et al., 2026

Our fingerprints , patterns on whale flukes , and fur patterns on cheetahs are examples of the natural ways we can tell one individual animal from another. For an Amazonian treefrog called the egg-eating spiny-backed frog ( Osteocephalus oophagus ) , we need to look into their eyeballs. Fine black radial lines cross their golden irises, and form a pattern similar to our fingerprints. A study recently published in the journal Herpetozoa details the discovery.

The project began with study co-author Mélissa Peignier, a behavioral ecologist at the University of Bern in Switzerland, admiring frog eyes.

“At the time, I was doing my PhD, studying Allobates femoralis in the field in French Guiana,” Peignier said in a statement .…