The Eyeless Cavefish Astyanas mexicanus (image) Marine Biological Laboratory Caption This is the eyeless cavefish Astyanas mexicanus. These fish begin to develop eyes but then lose them as the embryo matures. They are also depigmented, unlike their surface-dwelling ancestors. This is one of the few cave animals in which the surface-dwelling ancestor is not extinct, which allows scientists to compare them genetically. Credit William Jeffery/MBL Woods Hole Usage Restrictions Please use with proper credit. Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.