IN THE HOLE WORLD

When I was a child, I went with my family to visit a water hole in the desert outside Wickenburg. The lonely hole was in a narrow, rocky arroyo, and several of us waited in the rocks above as the sun set. Dusk heat radiated from the ground, and maybe we talked, or maybe we were silent, I do not recall. What I do remember is birdcalls closing in around the hole quail cooing at each other beneath the tender whine of phainopeplas. Black-winged bats flitted in and out, and in the brush animals darted, small sounds of sniffing and moving. It seemed like a secret life the desert had.

More than anything, I recall the water hole itself, an indigo circle of evening sky shimmering in the bottom of an arroyo. That circle inscribed itself in my mind, the serenity of water in the desert, the night filled with life. What could possibly be more beautiful, more strange, than a bit of water sitting still in a hot, dry land? I grew up to become a water hunter. I walked back and forth across the state marking water holes on maps, sometimes staking my life on them. In the southern part of the state, where water holes are known as tinajas, you find them hidden in the declivities of dry, thorny mountains. They are situated where thunderstorm floods sometimes rage, scouring bowls and plunge pools from the bedrock. Water collects in these holes and slowly evaporates until weeks or months later all that remains is a dark, bubbly film, and then finally a green parchment of dried algae. For drinking, the earlier side of the cycle is preferred. Looking for water in the long desert of the Cabeza Prieta National Wildlife Refuge, I once followed bees. One by one they shot across the desert, coming and going from somewhere in particular. Jags of granite, bone white in the sun, stood around me, and I followed the bees up to a crack. Bees foamed around the mouth of a shadow, and as I leaned in close I could see a dark mirror inside, a pool hidden from the sun. Reaching a metal cup through bees, I took just enough to soothe my throat, like drinking baptismal water. Stare at these pools and you will detect a slow haze of motion inside. They are home to a wealth of tiny crustaceans: little pea-shaped creatures known as ostracods, and clam shrimp with their soft bod ies tucked into their own translucent shells. Few are bigger than a pinhead or a fingernail. In every other canyon or so, you will find fairy shrimp, their long, ghostly bodies cruising through shafts of light sometimes hundreds of miles from the nearest permanent water.

Some of these holes are so populated they look like zoos, and with every gulp, you ingest 10,000 living things. How did they get there? They blew in on the wind, or tucked in bird feathers, or were shat out as eggs of larvae by bighorn sheep or coyotes stopping by to drink. Water-hole ecology is ruled by an array of uncanny adaptations. Invertebrates dwelling in ephemeral pools have the ability to deter mine exactly how long water will last. Because they have complicated life cycles, they have got to time it just right so that they can either get out as a winged adult or make themselves into seed-like eggs before the pool dries. Each pool and each storm requires distinct calibration, some keeping water for months, and some losing it within a week. One observer visited an Arizona stock tank for the 19 days that it held water after a heavy summer rain. Nearly 20 species of inverte brates and amphibians appeared during this time, and he took note of each. Predaceous beetles, Eretes sticticus, hatched by the thousands from eggs laid by adults that flew in from unknown water sources. Their development followed the stride of this slowly vanishing pool. On the 19th day, at 10:30 in the morning, the pool came very near to drying. En masse, the beetles, which had only recently reached their adult phase, suddenly produced an intense, high-pitched buzzing sound. Then, as the researcher stood watching, the entire group lifted into a swarm and set off to the southwest, disappearing at the horizon. Within an hour, the pond went dry. My own adjustments are simple calculations. I trek across the desert feeling the changing weight on my back, water supplies dwindling by a few quarts a day. When the lightness becomes disconcerting, I start scanning the horizon for a likely canyon or wash, any rain-catching topography. Finally finding the place, a circle of water, I sit at the edge and become one of the desert creatures that come out for tinajas.

In the north of the state, water holes are very different. They lie in beds of sandstone, and after a heavy rain it seems as if you are walking across the sky. There are places beneath the dome of Navajo Mountain where these holes grow as large as swimming pools and you count them by the hundreds. They are called waterpockets or kissing pools.

After a summer deluge, I went to one of these places, a terrain of sculpted rock, and in every dip there was water. Some holes were far deeper than others, thousands of gallons socked down into rock that looked like giant egg crates, water in each hold. In the deeper holes were troops of crustaceans known as Triops. These look like small horseshoe crabs, one or two inches in length, shield-like carapace mounted with two poppy-seed eyes, and a fleshy little rat tail at the end. They are, indeed, prehistoric; exactly matching their fossils of around 400 million years ago. They were sea dwellers back then, but when bony-mouthed fish evolved, Triops vanished from the sea and those that survived took up new lives in these far-flung water holes where fish cannot reach.

Now Triops survive by moving from one temporary water hole to the next, waiting out dry times in the form of eggs as parched as dust. It is a process known as anhydrobiosis - anhydro meaning without water, biosis meaning life. It is life without water, the only way to make it from one dry spell to the next out there. Anhydrobiosis is an adaptation common to many water-hole creatures. It is a form of existence in which all measurable life processes are shut down. Basically, these animals die but can, under the right circumstances, come back to life. Many invertebrates living in ephemeral water sources rely on anhydrobiotic stages to bridge the long, desiccating periods between rains. In their larval or egg form, they are able to withstand incredible pressures and doses of radiation that would quickly kill the adult phases.Unprotected cysts taken by a space shuttle to outer space and exposed for prolonged periods to cosmic radiation were still able to come to life when added to water back on Earth. Like pollen grains, the cysts of each species are uniquely shaped, with hooks or wings that grab onto passing animals or catch the wind in search of the next rain, the next water hole. They are models of physical endurance and patience.

When the rains come and the holes fill, life quickly springs from (or into) the water. The aquatic backswimmer Notonecta, a predator that the crustaceans would rather not encounter, flies in search of water holes. It seeks polarized ultraviolet light reflected from smooth bodies of water, the same method used by water striders and dragonflies. Ultraviolet sensors are located in the lower portion of its compound eyes.Notonecta flies with its body tilted 15 degrees to the horizon, placing these UV sensors at a level that will be struck by polarized light off a flat surface, initiating a dive-and-plunge response. Sometimes you hear them pinging off of your car hood at night because they think it is a water hole. Once, sitting in the desert with a cup of water in my hand, I was bombarded by backswimmers. Five of them made a bull's-eye into the cup, its mouth just 4 inches wide. I was holding their entire water hole in my hands.

Often in the summer, the waterpockets are dry. Sandstone becomes a bare face burning in the sun. During such a summer day, I stopped by a hole I had used in past years, and no matter how dry the season had ever been, I had always found water there. Not this time. The land was absolutely parched.

I set a camp on a whaleback of sandstone, and in the evening sat with my knees curled up watching thunderstorms on the horizon. They rolled off the Kaibab Plateau over the Grand Canyon and fanned into the surrounding desert. Bellies flashed with lightning, each storm trailing sheets of rain. A few lucky places were drinking, I thought. I laid back and fell asleep facing the sky, no need for anything but a wool shawl underneath me.

In the middle of the night, I awoke to a white bolt burning into my eyelids. I sat up in a restless wind just as the air ruptured with thunder. Half the sky was black, a thunderhead passing overhead. Within a minute, rain hammered the ground. I stuffed my gear into a protected nook and sat it out. The night was plenty warm, rain a relief on my skin, soaking through my clothes. It began to strike so hard I covered my face, head between my knees, my back a wet shield against the sky.

When the rain let up a half-hour later, I lifted my head. Water ran out of my hair, down my face, into my mouth. In the coming quiet, I heard burbling and grumbling as water sheeted across bare ground, overtopping holes, looking for places to stop. After an hour, the sound dwindled into drips that sounded like chimes on the rock.

In the morning, I awoke to water in every hole. Deeper holes were filled with hundreds of gallons of greenish-red fluid that would eventually settle and become clear. I knelt at one of these deeply colored pools, cupped my hands, and drank. It tasted of everything living and dead in the desert, the land washed clean. Drinking such freshly scoured water was not necessarily a wise thing to do, but it seemed like such a blessing, I could not help myself.

Life zinged in my stomach and I cramped into a knot. The pain took a minute to pass, a jolt of pure water-hole ecology. These holes had been waiting, floors packed with cysts silently prepared for any touch of moisture. When the water came, life erupted and I could feel it in my body, the sharp taste of the desert being born again.