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Current Affairs

A 100 million-year old fish in Kerala

Date: 27 October 2020 Tags: Biodiversity

Issue

A new type of fish was discovered in the watery underground rocks of Kerala that scientists have named “Gollum”, after Lord of the Rings character.

 

Background

Aenigmachanna gollum belongs to an old family of fish, called dragon snakeheads, which retains its primitive characteristics after all these millennia.

 

Details

  • Besides the Gollum, a sister species has also been discovered called Aenigmachanna mahabali. The scientists call the find one of the most exciting in the fish world of the last decade.

  • The discovery of a new family of fish is very rare. The dragon snakeheads have evaded scientists till now because they live in subterranean aquifers and come to the surface only after heavy flooding from rain.

  • The closest relative of the family Aenigmachannidae is the Channidae, of which at least 50 species can be found in the streams and lakes of Asia and tropical Africa. According to molecular analyses, the two families split from each other 34 million to 109 million years ago.

  • This may indicate that Aenigmachanna is a Gondwanan lineage, which has survived break-up of the supercontinent, with India separating from Africa at around 120 million years ago.

  • The lack of evolution can be seen in the shortened swim bladder of the dragon snakeheads as well as fewer vertebrae with ribs.

  • These indicate that the family is less specialised than regular snakeheads. The family also has eyes and a reddish brown pigmentation, which is unusual as most subterranean fish are pale and have no eyes.

  • Unlike the Channidae, the Aenigmachannidae also lack the suprabranchial organ that allows the former to breathe air and proliferate widely.

  • Such taxa have previously been characterized with the term ‘living fossil’ starting with Darwin or have been referred to as ‘basal taxa’.

  • They exhibit a striking level of morphological stasis as evidenced by a surprisingly large number of primitive characters compared to their extant sister group.

  • The researchers say that the area where Aenigmachanna was collected is part of the Western Ghats – Sri Lanka Hotspot, which is among the richest biodiversity hotspots in the world.

  • Ten other species of subterranean fish have been discovered in the aquifers. This area also services around six million wells in the region.