Eyes Are A Lot More Expensive Than We Thought

The Brain





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This eyeless Mexican cavefish is saving considerable energy by doing without sight. uttelvaserova Stuchelova/Shutterstock

The eye is such a valuable organ that it has evolved independently more than once, but it turns out animals pay a surprisingly high price for perceiving part of the electromagnetic spectrum. For one species of fish vision can consume as much as 15% of its energy intake, according to work published in Science Advances.