How can you eat, eat, eat–and stay healthy? Ask a blind cavefish.

Cavefish enjoy the ultimate in food binges.
Can any species eat as much as it wants–and stay healthy? Yes: blind cavefish, scientists are finding out. (Photograph: Nicolas Rohner)

Barbecues and clambakes. Ice cream and berry pies. Summer is the season of food, food and more food.

Is there a way to binge and still stay healthy?

For answers, look far underground, say scientists, to the denizens of darkness: blind cavefish.

Blind cavefish may be small, but they clean cave floors bare of a single morsel. (Photograph: Nicolas Rohner)

Biologists studied blind cavefish, Astyanax mexicanus, living in freshwater pools in deep caves in Mexico. The researchers compared the cavefish with their surface-dwelling piscine relatives, which have retained the ability to see.

In the caves’ sunless, pitch-black environment, no primary producers like plants exist. “So cave inhabitants rely entirely on food chains with origins on the outside,” says geneticist Clifford Tabin of Harvard Medical School in Boston, Mass., who led the investigation. The results were published on July 13, 2015, in the journal Proceedings of the National Academy of Sciences.

How do blind cavefish get their meals? Mostly through seasonal flooding when rivers bring tidbits to the caves, and from what cave-roosting bats leave behind. “As a consequence,” says Tabin, “the food supply is very infrequent.”

Seasonal river carrying food for cavefish.
Food drop: rivers that flow into Mexican caves bring a buffet for blind cavefish. (Photograph: Nicolas Rohner)

Staying alive…and satiated

To deal with the challenge of existing on little more than intermittent smorgasbords, cavefish survive by constantly chowing down when food is around, dramatically increasing their body fat. “The fish are very fat, much fatter than their surface-dwelling kin,” says geneticist Nick Rohner, also of Harvard Medical School.

Cavefish store as much fat as possible to tide them over until the next feast. “By doing that, blind cavefish have —> Read More