Ocean Watch

Monday, September 7, 1998

How to clean the beach
and feed crabs at once

EARLIER this summer, I was walking down Kailua Beach with a friend when he bent over a freshly beached Portuguese man-of-war. "Watch this," he said, picking the creature up by its blue bubble, its long, stinging tentacle dangling in the breeze.

He studied the waves for a few seconds, then when one broke high on the sand, tossed the man-of-war into the receding flow. Predictably, the inch-deep water began dragging the animal back toward the ocean.

Just when I was beginning to wonder about the point of this little demonstration, the man-of-war jerked to a halt. It held fast in the surf for a few seconds, then once again floated free. Except now, its long, stinging tentacle was gone. This Portuguese man-of-war had become a Portuguese man-of-peace.

Although I hadn't actually seen it, I knew what had happened during those brief seconds. A mole crab, lying in wait just under the sand at the surf line, had spotted the passing tentacle, and with astonishing speed jumped up, snagged the food, then reeled it in to eat at its leisure.

I knew these crabs did this, but had never seen them in action.

"Do it again," I said, delighted to learn this new game.

He picked up another nearby man-of-war, waited for the right moment, then tossed.

This time, I kept my eyes on the sand just beneath the blue creature.

And sure enough, for a split second, I got a glimpse of half a dozen smooth white bodies, all about one-inch long, jumping up for the prize as it passed by.

Mole crabs, sometimes called sand turtles in Hawaii, live beneath the sand near the surf line. These oblong crabs back into the sand, rear end down, with eyes and antennae just breaking the surface. When tiny pieces of plant or animal matter drift past, the crabs catch it on their feathery antennae, then suck it into their mouths.

But when a big chunk of food -- such as a Portuguese man-of-war tentacle -- comes their way, they leap up, grab hold with their little legs and haul it underground.

This happens with such amazing speed, it's often hard to see. After I wrote about these crabs last February, several people told me they spent hours at a beach looking for them but never saw even one.

dc2 NOW, thanks to my friend, I can share this way of "fishing" for the crabs. And this is my kind of fishing. It's active fun, helps the crabs get a meal and cleans the beach of stinging tentacles.

After I learned how to feed the mole crabs, I hurried down the beach to find more men-of-war. Soon, my friend and I were good at it, and we could coax the crabs into showing themselves for a second or more.

Interested people stopped to watch. One woman, however, yelled at us for throwing stinging tentacles around and wouldn't listen to our explanation.

Some people just don't know how to have fun.

I don't know if every beach in Hawaii has mole crabs, but Kailua Beach has plenty. So the next time the wind blows Portuguese men-of-war into the bay, don't stay home.

Go to the beach and feed the crabs.