Wednesday July 19, 2023
PhysOrg —
A team of marine biologist from James Cook University and University College London has found that blind cavefish living in dark caves in Mexico produce cells that are responsive to light. In their paper published in the journal Proceedings of the Royal Society B, the group describes their study of several samples of blind cavefish.
Prior research has shown that fish living in the waters of a cave complex in parts of Mexico and the U.S. have all evolved from the same species of surface river fish. And because the fish in different caves have evolved independently over differing periods of time, from tens of thousands to millions of years, they have different features relating to adaptations to living in the dark. Those that have had less time to evolve, for example, still have eyes, though most no longer function. Those evolving over longer periods have lost their eyes altogether.
Prior research has also shown that as the fish evolved, they slowly lost their circadian rhythm and many have greatly reduced sleeping times. Most have also developed a stronger sensitivity to vibrations, allowing them to sense movement in the water around them—useful for both navigation and finding food.