Time for a walk! Let’s go to a forest, or even a woodlot near your house and ask, how many different groups of animals will you find there? Not just in plain sight, but underfoot.
Well, says E. O. Wilson, Harvard’s most famous biology professor, in his newest book, Half Earth: Our Planet’s Fight for Life, you’ll see lots and lots of insects, spiders, mites, birds, caterpillars, frogs, millipedes, centipedes, crustaceans, moles, beetles, shrews, snails, slugs, earthworms, and roundworms, not to mention a whole lot of animals you can’t see without a magnifying glass. But altogether, Professor Wilson says, seven different animal groups (phyla) will show up in the forest. Remember that number: seven.
To the Beach!
OK, done with the forest. (There’s a point to this.) We’re going to jump in the car and drive to a sandy, open beach, presumably one next to a sea or an ocean.
After the woods, the beach looks almost vacant—empty of living things. But here’s Wilson’s bombshell:
“The surf may at first seem lifeless, composed of water and soil and washed clean. The opposite is true … Among the grains of sand in the surf zone, you will in time find twice the number of phyla.”
Twice? No way. He’s claiming there are twice as many different groups of creatures at the shore as there are in the forest. (We’re not taking population numbers here, we’re talking diversity.) Professor Wilson counts 14 different animal groups (or phyla) at the beach versus seven in the woods.
I am now imagining myself at the shore—staring at sand, water, foam, plus the occasional seagull—and I’m wondering, who is he talking about?
There are, of course, shorebirds, crabs, clams, beach flies, and sea stars. But then he tells me that down below my feet, teeny little worms are wriggling away through the sand, treating every grain as a dinner plate, feasting off the even tinier microorganisms (meiofauna) deposited by the ocean. The water washing over my feet isn’t empty; it’s got animals too. It has little wormy-looking things with names I don’t know—gastrotrichs, gnathostomulids, kinorhynchs, priapulids. I’ve never heard of them. But they’re there, squiggling, floating, crawling everywhere at the beach. How many are there?
Nobody knows, says Wilson. “Earth,” he says, is “a little-known planet.” People think scientists have identified most of the species on Earth. They haven’t. They’re not even close.
Back in 1758 Carl Linneaus, a Swedish scholar, decided to name all the plants and animals in the world. He got to about 20,000 species.
Today, the official count is just over the two million mark, with new species being added, Wilson says, “at the rate of about 18,000 a year.” The biggies on Earth—mammals, birds, fish—are mostly accounted for, but the teeming world of lesser creatures—the invertebrates, often tubed, small and unnoticed—there could be millions of them, doing who knows what out there.
That’s why beaches (and sea bottoms and oceans and ice) are virgin territory to biologists. They are finding not just new species in these spaces, but astonishing varieties co-mingling—a rich mix of phyla— where you wouldn’t expect them to be. If beaches are busier than forests, who knows what will turn up on sea bottoms?
You may say, That’s nice, but I’m no scientist, so these little animals? I don’t know ‘em, don’t need ‘em, don’t miss ’em, don’t care. But Wilson says, “We need to know.”
When you go to the beach and sink your feet into clean white sand, it helps to understand that worms below called polychaetes have been licking or swallowing grains all year to give the sand that texture. It’s like finding a sanitation department you never knew you had. If those worms disappear, then you’d notice. But then it’d be too late.
Wilson guesses there are 356,045 miles (573,000 kilometers) of shoreline on our planet, “almost exactly the distance from Earth to the moon.” So even if beaches seem like skinny little stretches to you, they add up. (Clump all the beaches together, and you’d get an area the size of Germany, he says.) That’s a lot of planet we’ve only begun to explore. Yes, we know about the biggest creatures in these places, but it’s time to meet the smallies—the almost invisibles—before we accidently lose the ones we need, the modest little creatures who, calling no attention to themselves, make our world so wonderfully livable.
Professor Wilson’s newest book is called Half Earth: Our Planet’s Fight for Life. It’s his 32nd, I think. He just doesn’t stop. He’s written about ‘superorganisms’—sometimes I think he is one.