Air Date: Week of August 4, 2000

Watch where you spread out your beach blanket this summer! Living On Earth commentator Sy Montgomery finds a complete cosmos of tiny life in that supposedly barren strip of sand.

Transcript

CURWOOD: If you're on the beach this August, you could easily find a bunch of kids digging a deep hole, imagining themselves coming out the other side of the world. Digging to China is what a lot of us called it when we were kids. They might not make it to China, but these kids will reach entire communities of creatures, even if they barely make it a couple of feet down. As commentator Sy Montgomery explains, there are whole miniature worlds teeming with life just below our towels.

MONTGOMERY: The world of beach sand is a place of astonishing wonders. Each grain can claim a rich history, and a stretch of supposedly barren beach can support millions of hidden lives. Beach sand is no desert. The creatures who live here are masters of camouflage and concealment. Tiger beetles, sand fleas, and mole crabs hide in sandy burrows. Moon snails hunt up to a foot beneath wet sand. Piping plovers' sand-colored eggs and plumage are so perfectly matched to their surroundings that most people never realize these birds nest on bare sand on some of our busiest beaches.

And then there is a whole specialized cosmos of creatures who've adapted to living and moving in the spaces between individual sand grains. In the wet sand beneath your feet, the miniature neighborhood of individual sand grains is populated by tiny creatures collectively known as interstitial fauna. This diverse group includes the world's smallest mollusks, worms only 1/16 of an inch long, and tiny crustaceans. There are also weird creatures known as water bears, with 8-clawed legs but no heart or respiratory system.

To these animals, the sand grains are like giant stacked cannonballs on a New England town square. The spaces between them seem copious. To move between them, most of these creatures wiggle like snakes or propel themselves with beating hairs called cilia. Many interstitial animals also possess an array of sensors to tell them which way is up, a mini-version of our inner ear, and whether it's dark enough. Sunlight is usually bad news. And they also have special organs to attach themselves to individual grains, so they aren't washed away each time a wave comes by.

The sand on which we walk and lay our beach blankets is a world rich with beautiful and intricate lives we cannot even see, but which we nonetheless can care for and respect. Beach sand allows us, as William Blake wrote in his Auguries of Innocence, "To see a world in a grain of sand and heaven in a wildflower, hold infinity in the palm of your hand and eternity in an hour."

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CURWOOD: Living on Earth commentator Sy Montgomery is author of Nature's Everyday Mysteries.