Mystery #4Tier 2-3evolution / adaptation
Why did cave fish lose their eyes?
Deep in pitch-black caves live fish that are completely blind, and many have no eyes at all, just smooth skin where eyes should be. Yet their relatives in sunlit rivers see perfectly. Why would an animal lose something as useful as eyes?
Your guess
What's your hunch about why fish living in total darkness would end up with no eyes?
There's no single magic word to type, have a go in your own words, then reveal the answer to see how close you got.
Make a guess to unlock the hints and the answer.