Squelching in pitch darkness of the wet evergreen forests of Kalakad Mundanthurai Tiger Reserve, I was distracted by phantom feelings of leeches crawling up my legs and of spiders in my hair. Biting down hard on these thoughts, I used my cell phone’s shallow light to figure out my next mossy foothold in a stream.

Seshadri KS, a researcher and PhD student with the National University of Singapore, had already reached the spot. I could see his and his field assistant’s shadowy figures move in the distance against torch light. Hunkered down in a dense patch of bamboo reeds, Seshadri was checking on his muse – Raorchestes chalazodes, or the Bubble-nest frog. Slightly more than an inch-long, this frog was rediscovered in 2011 after being considered lost for more than a century. And it turned out to be unique in more than one way.

R. chalazodes, an arboreal frog, has a novel reproductive technique. It squeezes its body into bamboo reeds through slits to lay its eggs, which bypass the tadpole stage to develop directly into froglets. In another unusual behaviour, the male frogs also provide devoted parental care.

In these wet, dark forests, Seshadri is studying several clutches of eggs across thickets of bamboo to find out how the fathers protect their young. He uses an innovative technique of inserting an endoscope, usually used for pipe inspections by engineers, into the reeds to observe the male frog. Looking through one, I saw a frog that stared suspiciously at the mouth of the endoscope with its gorgeous yellow-checkered eyes. Sometimes it felt tempted to lunge at it, perhaps in a bid to protect its eggs, while other frogs hid behind their eggs.

Several dozen new species of frogs have been reported from the Western Ghats over the past few years but most of these have hardly been studied. The fact that we are still discovering new reproductive pathways shows how little is known. Frogs and toads in particular are interesting because they exhibit 40 different reproductive modes – mammals have just two.

Seshadri remembers how excited he was when he first noticed this critically endangered bush frog squash itself into the bamboo and why it pushed him to found more. “There are several evolutionary questions that could be answered by studying this fascinating group of frogs," he said. "What goes on inside the bamboo internodes is still a mystery."