Many animal species have adapted to survive and even evolve without sight, often relying on other senses – here are 10 blind animals with next to no vision <\/p>
Just as evolution via natural selection<\/a> can give, it can also taketh away. If an animal lives in an environment in which a particular trait becomes unnecessary, then that trait may become reduced \u2013 or even lost altogether.<\/strong><\/p> This might be the wings of large flightless birds<\/a>, or the diminished pelvic bone still seen in snakes. It can also be a sense, like vision, and the eyes that grant it. Animals that live in the dark \u2013 whether that be underground or in the deep sea \u2013 are often found to have greatly reduced vision, eyes that are obscured by skin or hair so as to render them non-functional, or even lack eyes entirely. But what is the point of getting rid of an eye, even if it’s not used? Indeed, natural selection only works on traits that influence survival and reproductive success in some way.<\/p> There’s also an evolutionary process that goes some way in explaining the loss of certain useless features: genetic drift. Genetic drift is a random process by which the frequency of a trait in a population (and particularly a neutral one in terms of survival and fitness) can change. This process may work on eyes if they don\u2019t provide any meaningful advantage.<\/p> However, it doesn’t fully explain why blindness can evolve as rapidly as it does in some dark-dwellers. The general idea is that there must be a cost to having eyes \u2013 both in the making of them and in the upkeep. Eyes, though of course very useful in the light, may become a disadvantage. It takes energy to form them and they are vulnerable and easily damaged. In the dark, the blind may become the fittest.<\/p>
\u00a0What is genetic drift?<\/h2>