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Snakehead fish species found in Kerala a living fossil, belongs to unique family, study says

The fish, named after a character from the 'Lord of the Rings' fantasy novel, dwell in dark groundwaters, and are known to be usually found in Africa and Asia.

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New Delhi: A team of scientists have determined that a species of snakehead fish discovered in the Western Ghats in Kerala belongs to a unique family distinct from fish species found in the world.

Named after the creature ‘Gollum’ from the epic fantasy novel The Lord of The Rings, authored by J.R.R. Tolkien, the Aenigmachanna gollum was studied by scientists from India, Germany, the United Kingdom and Switzerland. Their findings were published Wednesday in Scientific Reports.

Snakehead fish are freshwater species, usually found in Africa and Asia. They are predatory fish distinguished by their long dorsal fins, large mouths, and shiny teeth.

What is most interesting about the Gollum snakehead, according to the study, is that scientists describe it as a ‘living fossil’.

The fish descend from an ancient gondwanan lineage that survived the break-up of the supercontinent and the northward drift of the Indian subcontinent about 100 million years ago.

The fish, which dwell in the dark groundwaters, remained isolated from the rest of the world, which is why their behaviour and characteristics did not evolve much over these hundred million years. 

As a result, they serve as ‘living fossils’ providing a window into prehistoric marine life, the study said.

“Throughout my career, I have worked on many strange fish, but the Gollum Snakehead is easily the weirdest of them all. If I had been asked whether such a fish existed in the Western Ghats or anywhere in the world, I would have said, no way,” said Ralf Britz, from Senckenberg Museum at Dresden, Germany, who led the study.

Also read: Why you should not order the Basa fish at Indian restaurants

Underground species discovered in wells or taps

Two specimens of the fish were discovered accidentally about two years ago. A local enthusiast in Kerala found them in the paddy fields of Kerala, shortly after they were flooded during the devastating August 2018 deluge.

Having never seen such fish before, the person shared pictures of it on social media, following which Rajeev Raghavan, assistant professor at the Kerala University of Fisheries and Ocean Studies, first spotted it. Raghavan is one of the authors of the study. 

“Usually, scientists look for new species by throwing nets into rivers or ocean systems,” Raghavan told ThePrint. 

“However, there is no way of monitoring or deliberately catching fish species that live under the surface of Earth,” he said. 

Such species are found either when people empty their wells in the summer in preparation for the rainy season or when individual fish get into taps that are used to source groundwater

The Aenigmachanna family of fishes has another member called ‘Aenigmachanna mahabali’, which was also discovered in Kerala a year ago when local residents were cleaning out a well.

Both gollum and mahabali — the latter named after the asura (demon) king believed to have lived underground — were initially thought to belong to a snakehead freshwater fish family known as Channidae.

However, high-resolution CT scans of the fish revealed that Aenigmachanna gollum has a large number of primitive characters. Further genetic analysis of the fish suggested that the family was separated from the Channidae family between 34 and 109 million years ago, said the study.

‘We may be losing unique habitats’

The subterranean ecosystems of Kerala harbour some of the planet’s most bizarre species of fish such as Horaglanis krishnai, Kryptoglanis shajii, Aenigmachanna gollum and Monopterus digressus, according to the study. 

Many of these species are blind, pigment-less, and have peculiar morphological characters that are otherwise not seen in species found in surface waters. Around 10 such enigmatic species of subterranean fish have been discovered in Kerala in recent times.

However, such subterranean ecosystems are under high levels of threat due to indiscriminate ground water extraction and pollution, and introduction of alien species in the dugout wells, Neelesh Dahanukar, research scientist at the Indian Institute of Science Education and Research, Pune, who co-authored the study, said in a statement.

“As a result, we may be losing unique habitats and species much before they are known to science,” Dahanukar said.

The team knows very little about the behaviour of the fish — what they prey on, for example — since it is difficult to monitor life under the surface of Earth.

“Identifying its mechanism of survival in extreme subterranean habitats could help us understand the reasons for retention of primitive characters and what makes them living fossils,” said Siby Philip, assistant professor at Nirmalagiri College, Kannur, in a statement.

Also read: Scientists accidentally discover first animal that doesn’t need oxygen to survive


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