Biologist: Marine animals known as box jellyfish have eyes with well-formed lenses capable of producing sharp images that reveal fine detail. But the box jellyfish' s retinas are too far forward to receive a clear image
these jellyfish can receive only a blurry image that reveals prominent features of objects but not fine detail. This example shows that eyes are adapted only to an animal' s needs rather than to some abstract sense of how a good eye would be designed.
Box jellyfish have a need to detect prominent features of objects but not fine details.