January 22, 2014
A shoal of bizarre-looking cave fish has gone on display at Newquay’s Blue Reef Aquarium.
Found in the total darkness of subterranean cave systems and caverns in Mexico, the blind cave fish is a freshwater species that has, over countless generations, lost the ability to see.
The fish is a type of tetra, which is still common throughout the country. Scientists believe that in the distant past a number of these surface-dwelling fish made their way deeper and deeper in to underground cave systems.
The blind form of the Mexican tetra is different from the surface-dwelling form in a number of ways, including having unpigmented skin, having a better sense of taste, and by being able to store four times more energy as fat allowing it to deal with irregular food supplies more effectively.
Rather than relying on sight, they instead use a highly-developed sense organ, known as the lateral line, to detect movement and vibration in the water.
Currently, there are 29 known cave populations, from three geographically distinct areas in north eastern Mexico.
Blue Reef’s Steve Matchett said: “The story of this particular species is one of the most bizarre and fascinating in the world of fish.
“It illustrates the extraordinary adaptations which species can gradually undergo over a huge time period to suit it to its specific environment.
“No one is entirely sure of the actual reason for the fish to effectively grow scales over their eyes.
“It may be the risk of having exposed eyes which were of no use, and could potentially get damaged, was sufficiently important for the fish to evolve in such a way as to prevent this from happening.
“Unnecessary energy which was formerly used to develop complex eyes could also now be used instead for extra growth
“Alternatively it could just be that, as their eyes were of no importance, the fish was not subject to the normal rules of natural selection and eye defects or diseases did not affect the species’ ability to survive,” he added.
Issued by Blue Reef Aquarium. For more information please contact Steve Matchett on 01637 878134.