Guwahati: Deep in the forests of Arunachal Pradesh, a small brown toad that looks like a fallen leaf suddenly lets out a shriek — and bites. Over 2,500 kilometers away, in the lush rainforests of Kerala, a bright yellow frog rises tall on its legs, as if to stare down danger.
These startling scenes are not from a nature documentary but from a new study by researchers at the University of Delhi’s Systematics Lab, led by amphibian expert Professor S.D. Biju. The team has documented, for the first time in India, two striking defensive behaviors among native frogs — one that bites and shrieks, and another that intimidates predators by raising its body.
The findings, published in the scientific journal Herpetological Notes, describe the biting and distress-calling behavior of the Apatani Horned Toad (Xenophrys apatani) from Arunachal Pradesh and the body-raising display of the Bicolored Frog (Clinotarsus curtipes) from Kerala. Together, these discoveries open a new window into India’s untold amphibian world.
A Frog That Bites and Screams in Arunachal’s Forests
The nocturnal Apatani Horned Toad, found in the Tale Valley Wildlife Sanctuary in Arunachal Pradesh, relies on its perfect camouflage to remain unseen among leaf litter. But when approached, this small amphibian transforms into a fierce defender — inflating its body, opening its mouth wide, emitting a piercing shriek, and even biting its aggressor.
During field observations, researchers used a twig to simulate a threat. The frog immediately puffed up and bit the twig with such force that it had to be pulled free. It also emitted a series of sharp distress calls, acoustically resembling the screech of a cat.
“This was the first time we observed such an intense combination of behaviors — inflation, shrieking, and biting — in an Indian frog,” said Prof. S.D. Biju, who led the study. “It’s a reminder that our forests still hold countless secrets.”
While such defenses have been recorded in some tropical frog species worldwide, this marks the first report of both biting and distress-calling behavior among India’s horned frogs (Megophryidae family).
The Kerala Frog That Stands Tall
In the Western Ghats, the diurnal Bicolored Frog has its own dramatic defense tactic. When disturbed, it stretches its limbs vertically and raises its body off the ground, exposing its dark ventral surface — a visual illusion that makes it appear larger and more intimidating.
Researchers observed this “body-raising” or deimatic display repeatedly when the frog was lightly prodded with a twig. The behavior, lasting several seconds, likely serves to startle potential predators.
“This is the first documentation of such a body-elevation posture among Indian frogs,” said Tage Tajo, the study’s lead author. “It’s an example of how even familiar species can surprise us when observed closely in the wild.”
Why These Discoveries Matter
Globally, around 7,800 frog species are known, and about 650 of them exhibit defensive tactics ranging from camouflage and secretion to posturing and biting. India alone has 419 recorded frog species, but their behavior remains vastly understudied.
“These new findings fill an important gap in our understanding of Indian amphibians,” Prof. Biju said. “They show that even common species can have rare and fascinating adaptations that help them survive.”
The discoveries also underscore the ecological importance of India’s biodiversity hotspots — the Himalayas and the Western Ghats — where many species are found nowhere else on Earth.
“These frogs remind us that the wild still has surprises hidden in plain sight,” Prof. Biju added.
A Final Word from the Researchers
“These new findings fill an important gap in our understanding of Indian amphibians,” said Akalabya Sarmah, another lead author of the study. “They show that even common species can have rare and fascinating adaptations that help them survive. For us, each discovery like this is a small reminder of how much more there is to learn from nature — if only we take the time to look.”
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