Scientists have described Rakthamichthys anchi, a new species of blind, blood-red swamp eel, from dug-out wells in Assam's Goalpara district.
The discovery was published in the international taxonomy journal Zootaxa.
The species measures between 25.5 cm and 31.8 cm and resembles a moderately sized earthworm.
Its blood-red colour comes from blood vessels visible through nearly transparent skin; 'anchi' is a Garo word meaning blood.
The genus Rakthamichthys consists of groundwater-dwelling swamp eels endemic to India.
Phreatobitic animals live exclusively within the phreatic zone, the saturated groundwater below the water table, where no light ever reaches. Evolution in permanent darkness produces a recognisable set of traits called troglomorphy: eyes are reduced or lost entirely because vision confers no advantage and maintaining eyes is metabolically expensive; body pigment disappears for the same reason; and other senses, particularly the detection of vibration and chemical cues, become more acute. The blood-red appearance of this eel is not pigment at all — with skin almost devoid of pigment and nearly transparent, the blood vessels beneath simply show through. Such species are typically found by accident, in wells and springs where humans breach the aquifer, which is why groundwater fauna is among the least documented of all animal groups.
Simple Analogy: An animal that never sees light discards its eyes for the same reason a household discards an appliance it never switches on — upkeep costs something and delivers nothing.
Publishes the annual Animal Discoveries report recording new faunal species described from India each year.
The suite of adaptations — loss of eyes and pigment, enhanced non-visual senses — shown by cave and groundwater animals worldwide.
India is the world's largest extractor of groundwater, which makes aquifer-restricted species particularly vulnerable.
The species name comes from the Garo word for blood; Garo is spoken in Meghalaya and adjoining parts of Assam.
India's framework law for conservation and access to biological resources, amended in 2023.
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A genus of groundwater-dwelling swamp eels of the family Synbranchidae, endemic to India.
The saturated groundwater zone below the water table, where phreatobitic animals live.
The set of adaptations shown by animals living permanently in darkness, including loss of eyes and pigment.
Found naturally in a single defined geographic area and nowhere else.
An international peer-reviewed journal for animal taxonomy in which new species descriptions are published.