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July 11, 2009


If you enjoyed our piece on porcupines and sex, you might find this interesting

Louisa Jonas, NPR - On the Delaware Bay shore, there's a swinging party that's been taking place for millions of years.

If you're a female horseshoe crab, then it's your night. You'll swim to shore, meet a special someone and he'll clasp onto the back of your shell. You and he will crawl onto the beach together, where you'll spawn at high tide under the light of the full moon.

But the mate attached to your shell is not your only tryst. On this night, you will mate with up to 13 males, all at the same time. Thousands of horseshoe crabs will pile on top of one another, glistening shells covering the beach for miles.

"We just love the whole phenomena of how once a year, for a season, they do this incredible mating on the beach," Keith Rutter says. "I don't know how anybody can watch this and not get excited about nature and science and how things work in the world."

Rutter and his family didn't travel from Silver Spring, Md., to Delaware's Pickering Beach just to watch the orgy. They came here to count.

The Delaware Bay shore is the site of the largest horseshoe crab spawning in the world, but in the 1990s the horseshoe crab population in the bay plummeted. So on this night, at the world's epicenter of horseshoe crab sex, volunteers in headlamps and waders will tally up the amorous crabs.

Horseshoe crabs are weird, like armadillos of the sea. Their shells look like armored helmets and their tails resemble swords. And then there are the eyes. They have 10 of them — including one on that spiked tail that helps them tell time. Their strange design is time-tested; they haven't evolved much for more than 400 million years. We're talking before the dinosaurs — before flying insects, even.

Scientists call horseshoe crabs living fossils. Master generalists, they've survived asteroids, volcanoes and ice ages. But on the beach, there's no such thing as safe sex. About 10 percent of crabs die upside down when they can't right themselves during spawning. . .

In one sitting, each female lays about 4,000 tiny green eggs that look like clumps of pesto in the sand. In a few weeks, only the luckiest of eggs will hatch and billions of eraser-sized horseshoe crab babies will wash into the bay.

Recent surveys suggest that the horseshoe crab population may be stabilizing, and everyone here hopes this latest count will show an increase in spawning. The crabs themselves are certainly doing what they can; even after the tide recedes, a few determined, solitary males patrol the beach, still scanning the deserted sand for a mate.


Anonymous Mairead said...

That's the major problem with random evolution: there's nothing that cares about the fate of individuals, or indeed the larger ecosystem (as we ourselves are now demonstrating).

It's enough to make any thinking person wish for a caring God.

July 12, 2009 8:18 AM  
Anonymous no offense but... said...

Contrary to Jiminy Cricket, Wishing won't make it so. Guess we'll have to make do with the incredible force/fuel/whatever that drives the miracle around us. It's rather like Smother's Bros. (Mom always liked you best) to expect the universe to adapt human standards. God help us.

July 16, 2009 12:28 AM  

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