The Desert's Resourceful Survivors

It's universally known water is the source of all life. That's still the case in deserts, where one can see the miraculous ability of organisms that adapt to drought by drying up and lying dormant, sometimes for centuries, until water returns.

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Commentator Ruth Levy Guyer reflects now on the amazing variety of life that springs up wherever there's a drop of water.

RUTH LEVY GUYER: You know that illustration showing a series of progressively larger fish in line, mouth to tail?

Well, that simplistic image is - I'm embarrassed to say - precisely how I thought of aquatic food chains for quite some time. I never considered roles for crab, shrimp or plants and certainly not for microorganisms. But then, boom.

In August 1985, oceanographers at Woods Hole published a dazzling story in Science Magazine, where I was working, that jolted my brain out of its intellectual hibernation. I can still see the vivid, glossy photograph of Riftia, the giant red tubeworms that were flourishing at hot springs that bubbled up through a rift in the ocean floor. Hanging out with Riftia, a mile and a half from the sea surface, were specialized clams, mussels, shrimp, limpets, anemones, fishes and worms.

I started thinking again about those ruby tubeworms and their buddies while reading about a man who hiked through the southwestern deserts, searching for water sources. He'd cross the most parched land and then discover a pool, a spring, water pockets, a creek. Wherever he found water, he found life.

Imagine an isolated puddle containing just a cup and a half of water teeming with swimming flatworms and larvae of tiny flies and of mosquitoes. Imagine island-like pools in bare rock loaded with fairy and tadpole shrimp. Miracle enough that the author found the water. But how did those organisms do it? The desert is not like the deep sea where progenitors can ride the waves from vent to vent. Desert water is discontinuous.

Apparently, a few desert organisms hitch rides in wind and rain. Others travel inside or on insects, birds and toads. But the most intriguing are the organisms that, long ago, adapted to drought by simply drying up when the water sources did. They would enter states of extreme hibernation. And by extreme, I mean, they could lie dormant for centuries. When the water came back, they did too. In the case of the tadpole shrimp, this adaptation works so well that not a single physical feature has changed in 200 million years.

I find it incredible that the freshwater shrimp and their distant saltwater cousins have both existed for 200 million years, yet in all that time, they've never met, as I do with my cousins to enjoy a leisurely long, cool drink together. And poignantly, were they actually to meet today, it would surely be Jonah-style - deep in the belly of the biggest feeder on the human food chain -someone sampling a menu's exotic offering, the mixed shrimp cocktail.

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ELLIOTT: Ruth Levy Guyer is the author of "Baby At Risk: The Uncertain Legacies of Medical Miracles for Babies, Families and Society."

That's ALL THINGS CONSIDERED from NPR News. I'm Debbie Elliott.

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