New species of blind eel that burrows through the soil discovered
Considered by many to be the least fish-like of fishes, swamp eels are a real oddity and rarely documented. Now Museum scientists have described an entirely new species.
The fish was discovered not in water but in damp soil. Museum researcher
'We were digging all day every day for caecilians in the Khasi Hills of Meghalaya, in the north-east of India, when I chanced upon this fish,' explains Rachunliu. 'This is the only specimen of the species, as we couldn't find any more.'
Compared to the two other species of swamp eel found in the region, the specimen was so distinct that even from this single individual the researchers could be certain it was a new species. It is described in the journal of Ichthyological Exploration of Freshwaters.
A burrowing fish
Even among the 34,000 or so species of bony fishes, swamp eels are rather weird.
Many swamp eels are found close to freshwater streams, making a living in the mud and between roots. But some have evolved far more
Some of these eels live in caves while others are found in aquifers deep underground, but a few actually burrow through the soil. This new species, for example, was found burrowing some 50
Unsurprisingly this means that very little is known about these ichthyological oddities, as those who study fishes tend to be looking in the water.
Living in the dark
Living an entirely subterranean lifestyle means that the fish has a suite of adaptations - including being blind. Ralf explains, 'We suspect that the eyes just never really develop. We can't say that for certain for this particular species as we don't have early life stages, but that is something I would expect.'
The vivid pink
This leads to another of their major adaptations, shared with other species of swamp eel. The damp soil helps to keep the eels moist, but not so much with breathing.
'All swamp eels rely on breathing air,' says Ralf. 'Their gill filaments - which most fishes use for oxygen exchange - are almost gone entirely.
This allows the fish to breathe air through the lining of their mouth. Yet this is not the case for the eels' entire lives: while adult swamp eels have no fins, the young eels do.
'The early larval stages have very large pectoral fins,' explains Ralf, 'and they use these as accessory gills instead of their mouths.'
An overlooked diversity
There are only 25 species of swamp eel described by science, but they have an interesting distribution.
'There are several species of swamp eel from South and Central America, then three species in West
This refers to the pattern of distribution of many species of animals and plants that evolved on the supercontinent Gondwana before it split to form South America, Africa, Antarctica, Australia
The latest eel was found in a very poorly known, remote part of India. Traditionally it has been regarded as a transitional zone between the Himalayas and the Indo-Burma hotspots, with few unique species of its own to speak of.
'But this has turned out not to be true,' Rachunliu explains. 'Rather than being a transitional zone, it seems to have its own set of species with deep evolutionary roots. It's a really fascinating area, but greatly
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