Cascade Frogs: New Amphibians from Northeast India

Cascade frogs get their name from where they live. They stay near cascades, which are small waterfalls. Their home is rocky streams that rush down forest hills.

• They belong to the genus Amolops.
• There are around 100 species of Amolops across Asia.
• They are also called torrent frogs or sucker frogs.

How they survive fast water

• Their tadpoles have a sucker on the belly.
• The sucker grips rocks, so the current cannot wash them away.
• Adults sit on wet rocks right next to the spray.

An old family

• DNA dating shows the group branched out about 32 million years ago.
• That was a time of big change in Earth’s climate and life.
• The early rise of the Himalayas shaped where these frogs live today.
• They spread across Asia in waves, from east to west.

The three new species

• Ammachi’s Cascade Frog (Amolops ammachi) was found in the Jampui Hills of Tripura.
• It is about 80 mm long. Its light-brown body has olive-green, net-like marks.
• It honours the late Kerala social worker Padmini Varkey. People called her “Ammachi”, which means mother.
• Sendenyu Cascade Frog (Amolops sendenyu) comes from Nagaland. It is named after Sendenyu village.
• Beautiful Cascade Frog (Amolops bella) comes from West Bengal.
• “Bella” means beautiful. Its green body has yellow-green or red-brown patches.

Five first records for India

• The team also found five known species never before seen in India.
• They are A. afghanus, A. nepalicus, A. wangyali, A. medogensis and A. bellulus.

How the study was done

• It was led by Prof. S.D. Biju of Delhi University.
• The fieldwork took over 15 years. It covered all seven northeastern States.
• The team studied more than 300 frog populations.
• They compared DNA. They also compared the bodies of adults and tadpoles.
• The paper came out in the Bulletin of the Museum of Comparative Zoology. Harvard University has published it since 1863.
• (The Hindu; Down To Earth)

The Northeast has hills, heavy rain and thick forests. Many streams cut through steep valleys. Each valley can hold its own kinds of frogs.

• Northeast India falls in two biodiversity hotspots: the Himalaya and Indo-Burma.
• Four hotspots partly fall in India: Himalaya, Western Ghats, Indo-Burma and Sundaland.
• There are 36 hotspots in the world.

What makes a hotspot?

• It must have at least 1,500 plant species found nowhere else.
• It must have lost at least 70% of its original plant cover.
• So a hotspot is both very rich and in danger.
• The idea came from scientist Norman Myers in 1988.

India’s amphibians

• India has about 496 amphibian species.
• Of these, 452 are frogs and toads.
• 42 are caecilians, which are legless and look like worms.
• Only 2 are salamanders.

Frogs are like a warning light for nature. When frogs vanish, something is wrong with the water, air or land.

• Frogs drink and breathe partly through their thin, wet skin.
• So pollution in water or air enters their bodies quickly.
• They need both water and land in their life.
• Damage to either one can harm them.
• This makes them good bio-indicators, or signs of a healthy place.

India’s “Frogman”

• Prof. S.D. Biju is often called the Frogman of India.
• In 2010, he started the Lost! Amphibians of India campaign. It searched for frogs thought to be extinct.
• The IUCN gave him the Sabin Award in 2008.
• His team also described the famous purple frog of the Western Ghats in 2003.

In 2023, a big global study checked the health of the world’s amphibians. It was the second Global Amphibian Assessment, published in Nature.

• It studied 8,011 species.
• It found 40.7% of them under threat.
• That makes amphibians the most threatened group of animals with backbones.

The main dangers

• Before 2004: disease and habitat loss caused most of the harm.
• The worst disease is caused by the chytrid fungus. It attacks a frog’s skin.
• Since 2004: climate change has become the top cause.
• Frogs need damp skin, so a hotter, drier climate is hard on them.
• Habitat loss is a close second. Cutting forests and damming streams destroys frog homes.