Zurich, Switzerland – Bright green with blue flanks and vivid orange eyes, the orange-eyed tree frog is as striking in appearance as it is rare in nature.

This nocturnal frog folds into a compact form during the day, resembling a green stone. From below, it looks like a suction cup pressed to the glass of its enclosure.

The frog’s ability to change color, a process called metachrosis, helps it communicate, camouflage, and regulate its body temperature.

Native to Costa Rica’s tropical forests, it prefers moist lower tree levels and is known for its loud repertoire of courtship and territorial calls.

But the species is endangered and already extinct in large parts of its range.

The biggest threat it faces is the chytrid fungus.

This deadly pathogen infects amphibians’ skin, thickening it and disrupting vital functions like water absorption, breathing, and thermoregulation.

The infection almost always proves fatal.

The chytrid fungus likely originated in Asia and spread globally in the 1980s. It is now considered one of the greatest threats to amphibians worldwide.

Forty-one percent of all amphibian species are threatened with extinction. The fungus affects every amphibian species in Switzerland as well.

Zurich Zoo is working to save the orange-eyed tree frog.

At its research station, keepers breed and study the species under carefully controlled conditions.

The zoo coordinates conservation, research, and education to fight amphibian decline.

Despite promising laboratory treatments for the fungus, applying them in the wild remains nearly impossible.

Zurich Zoo continues to lead efforts to protect amphibian diversity before it vanishes forever.

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