Young damselfish develop fake eyespots on their
dorsal fins to confuse their enemies.
Sometimes it helps to be exposed to your enemies at a young age.
Scientists think young damselfish develop fake eyespots – which fade when they grow up – to fool their enemies into not knowing if they’re coming or going. That way, a predator who thinks he’s attacking the front of the fish might actually be attacking the less vulnerable back of the fish, enabling the fish to escape serious harm.
Like having his head bitten off.
But is this really true? Biologists did an experiment where they took young damselfish who’d never been exposed to predators and exposed some to predators and didn’t expose others.
To expose them without killing them, they fooled the fish by placing a variety of harmless fish substitutes in their tank: a predator fish in a plastic bag, or the smell of a predator fish, or a harmless fish that looks like a predator but doesn’t eat meat.
The fish who were exposed to the harmless predators developed the fake eyespots, as well as other features that helped them, such as smaller real eyes, deeper bodies, and a more cautious attitude.
When they finally exposed the damselfish to predators, the innocent fish who had never encountered predators were at a disadvantage compared to the fish who encountered the predators.
Their disadvantage? They died five times more often.
Researchers find young angelfish grow fake eyes to ward off predators, PhysOrg>>