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By Pat Graham
August 3, 2009
Deserts harbor many stories.
A few years ago, I was talking with a retired Marine helicopter pilot who lives in Yuma, Arizona.
He recalled seeing tracks in the sand on one of his first flights over the training grounds east of town. He didn’t think anyone was allowed to drive in that area.
When he reported it, he learned they were tank tracks left decades earlier by General George Patton while he was training for battle in North Africa during World War II.
Deserts are fragile places. They heal very slowly, if at all.
Despite their fragility, deserts have great diversity. Unbelievably, the Sonoran Desert has an estimated 1,000 species of native bees.
What Lies Beneath
The Namib Desert is one of the world’s oldest. It stretches along the western coast of Namibia from South Africa north to Angola.
In fact, it is a desert on top of a desert. A fossilized desert of dunes lies beneath those we see today.
The Namib is the only desert in the world that has all of its known species from 150 years ago.
Some, like the black rhino and desert-adapted elephants, capture the imagination by their size and strength. Others defy imagination by adapting to the extreme conditions of this scorching desert in some unusual ways.
The long-legged beetle races faster than three feet per second from one clump of vegetation to another. If it stops too long it will die from hyperthermia. It is the only animal known to use exercise to cool itself.
The majestic oryx or gemsbok stops sweating to conserve water when heat is excessive. To avoid the trauma from overheating its brain, the Oryx has a network of fine blood vessels at the base of the brain.
Warm blood coming from its heart passes next to cooler blood from the nasal area to protect the brain despite a body temperature that can rise from 102 to 113 degrees F.
Amazing Adaptations
It rains very little in the Namib and some years not at all.
Thick fog pushes in from the ocean at times. So to conserve scarce water, the fog-basking beetle crawls to the crest of a dune, extends its hind legs and tilts forward so the condensation from the fog forms droplets of water on its shell that then slide down to its mouth.
Animals in arid climates are often adapted to filter as much water from food and other sources as possible. The shovel-snouted lizard has a lining that allows it to separate fresh water from the more saline body water in the rest of its system. In essence, it creates a reservoir of fresh water it can store for up to a month.
Grant’s golden mole spends the warm days burrowed in the loose sands, and then comes out at night. It has so fully adapted to this cycle of life, that it has lost the need to see so has evolved without eyes.
Life on a Warmer Planet
As I climbed the towering red dunes at Sossuvlei Park, the world’s tallest, I saw a lizard burrow into the sand and a beetle scurry across the sand.
As I climbed higher I could see the soft sands blow over the crest of the dune like snow off a mountain peak. The southwest winds sculpted a spectacular array of dunes. These desert sands quickly erased the sign of those who passed before me.
I wondered if the desert would ever get too hot and dry even for these well-adapted species. And while burrowing into the sand is hardly a solution for climate change, perhaps some of the adaptations these desert dwellers have evolved will spark ideas about how we can adapt to living on a warmer planet in the years ahead.
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Nature picture credits (top to bottom, left to right): Photo © Tim Ellis (Tracks in the sand); Photo © ibeatty (Hanging insect); Photo © Pat Graham/TNC (Namibia's majestic oryx).
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