A Fossil in the Flesh

The Purple Frog is often described as a “living fossil.” Why? Because it represents one of the oldest surviving lineages of frogs in the world. Genetic studies show that it split from its closest living relatives—the Sooglossidae frogs of the Seychelles—over 130 million years ago, when India was still part of the ancient supercontinent Gondwana. As the continents drifted apart, this lineage remained, isolated and hidden, until it was scientifically described only in 2003

The Secret Life Below Ground

Unlike most frogs, Nasikabatrachus sahyadrensis spends nearly its entire life underground. It is adapted to a fossorial (burrowing) lifestyle, emerging above ground only for a few days each year, typically in April or May, just as the first pre-monsoon showers arrive.

During this brief window, males call out to attract mates. What’s astonishing is that these calls come from underground chambers—they don’t surface to vocalize. The call itself is a series of low-frequency, pulsatile grunts, very unlike the melodic croaks we associate with frogs. With no external ears, it’s still a mystery how these frogs detect sound, but studies suggest they may sense ground vibrations

Tadpoles of the Torrent

While the adults live underground, the tadpoles are extreme specialists of the water. Once the female lays eggs in seasonal streams, the larvae hatch into tadpoles that look like tiny suction cups with tails. These tadpoles are rheophilic—adapted to fast-flowing water. Using specialised suctorial mouthparts and strong jaws, they cling to the surfaces of rocks in torrents and feed on the algae that grow.

Their morphology is so unique that for decades, they were known from local sightings and folk knowledge but were never linked to the adult form. Even today, local tribal communities recognise and sometimes harvest the tadpoles for food, which poses a growing conservation challenge

From Stream to Soil: A Metamorphic Marvel

One of the most dramatic transformations in the animal kingdom happens inside the Purple Frog. As the tadpole matures, it undergoes rapid and radical changes. The flattened, clinging body shape gives way to a rounded, muscular form perfect for digging. Skeletal remodelling includes the development of strong limb bones, ossified digging tools like the prehallux (a bony spur near the foot), and a wedge-shaped skull to push through soil.

This transformation is not just functional—it’s a switch from one ecological world to another: from clinging in fast-flowing water to tunneling through earth.

A Fragile Future for a Prehistoric Survivor

Despite surviving for over 100 million years, the Purple Frog (Nasikabatrachus sahyadrensis) now faces an increasingly precarious future. Listed as Endangered by the IUCN, its survival hinges on the delicate balance of seasonal monsoon streams and undisturbed forest soils—habitats that are rapidly disappearing.

Tadpoles require fast-flowing streams with rocky beds, while adults live underground and emerge briefly to breed. Habitat alterations due to deforestation, damming, and land-use change have led to a significant decline in suitable breeding grounds

Studies also highlight a troubling 59% drop in tadpole numbers over five years in some regions, largely due to harvesting by local communities for consumption during the monsoon season.

The Purple Frog’s limited known range (less than 5,000 km²), dependence on ephemeral habitats, and brief appearance above ground make it exceptionally difficult to monitor and conserve. However, these very characteristics also make it a compelling symbol for the protection of India’s Western Ghats biodiversity hotspot. Conservationists stress the urgency of long-term population monitoring, habitat protection, community awareness, to ensure this ancient voice of the monsoon does not fall silent forever.

The Mahabali Frog: A Cultural Connection

In Kerala, the Purple Frog is affectionately known as the “Mahabali Frog,” drawing a parallel with the legendary King Mahabali from Hindu mythology. According to tradition, Mahabali visits his people once a year during the festival of Onam. Similarly, the Purple Frog emerges from its underground habitat for a brief period each year to breed, typically coinciding with the onset of the monsoon rains .

This symbolic connection has been instrumental in raising awareness about the species. Conservationists have utilized this cultural link to engage local communities, creating educational materials that depict the frog as King Mahabali. These efforts have not only fostered a sense of pride and ownership among the people of Kerala but have also led to increased support for the frog’s conservation .

Recognizing its unique ecological and cultural significance, there have been proposals to designate the Mahabali Frog as Kerala’s official state amphibian. Such a designation would underscore the importance of preserving this ancient species and its habitat in the Western Ghats .

The Purple Frog Trail: A Tribute to an Enigmatic Ancestor

At Thavala Trails, we celebrate this ancient and iconic species with a special trail experience—The Purple Frog Trail. Designed for nature lovers, citizen scientists, and curious travelers, this seasonal trail takes you into the heart of the frog’s habitat during its brief annual emergence. Led by local experts and conservation researchers, this trail gives you the chance to:

• Visit breeding streams and learn how tadpoles survive monsoon torrents.

• Understand the underground life of adult frogs through guided storytelling.

• Participate in ethical citizen-science observations.

• Discover other monsoon-specialist species along the way.

A Symbol of the Western Ghats’ Secrets

The Purple Frog reminds us that there are still ancient mysteries underfoot. It teaches us patience, secrecy, and how much there is yet to understand about biodiversity. At Thavala Trails, we walk with reverence through its habitat, not just as spectators—but as guardians.