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Monday, July 6, 1998

Hawaii’s aama crabs help
keep its shorelines clean

While boarding my sailboat in the Ala Wai Boat Harbor recently, I spotted a baby bird floating dead in the water. It was sad seeing that downy little body there in the ocean, but I shrugged it off to natural selection and went about my business.

A while later, when I was leaving the boat, I noticed some commotion at the water's edge. To my surprise, a rock crab, or aama, was dragging the dead bird to a ledge near the waterline. No bigger than the bird itself, that crab tugged and hauled with amazing efficiency.

I watched for a while, then checked back a few hours later. The crab was gone and there wasn't a trace of the bird left. The little aama had performed its recycling chores perfectly.

These little scavengers do a fine job of cleaning up Hawaii's shorelines, but they have other uses too.

Not long after I moved here, a friend invited me to a baby luau. When I arrived at the party, I was shocked to see a row of spidery, black legs sticking out of the mouths of several children.

"They're eating aama," a friend told me. "Good with salt, yeah? Try one."

"You eat the shell?"

He pried the back off a dead crab and sprinkled some coarse salt onto the crab's innards. "Like this," he said, popping the creature into his mouth.

I'm not one to turn up my nose at unusual foods, but slurping raw crab guts was where I drew the line. I didn't do it. However, I did enjoy watching the kids do it. They sucked on those crabs like they were lollipops.

Over the years, as I prowled Hawaii's beaches and shorelines, I found aama nearly everywhere. These fast-running crabs are often at the top of the tideline on rocky shores, scavenging for just about anything they can find to eat, plant or animal, alive or dead.

In some places, it's common to find lovely crimson versions of Hawaii's aama. These look like red, dead crabs but they aren't. They're the molted shells of growing aama.

Examine one of these molts and you will find a paper-thin shell with a slit at the back. After reabsorbing much of the calcium from the old shell, the crab backs out and abandons it. The roomy new shell hardens soon after.

Their flat bodies and long legs are perfectly suited for life on Hawaii's wave-battered shorelines. When a wave approaches, the crab grips its rock with the spines on its legs, then hunkers down for the onslaught.

Once, I spent an afternoon at a rocky beach in Lanai watching several big aama nibble a dead, wedged fish while being absolutely pounded by waves. The crabs held their ground just fine.

Aama have some interesting predators. Once, near my boat slip, I saw a puffer fish lunge from the water and grab an aama that was basking near the edge. Another time, I watched a man catching the crabs with a simple tool that snags aama by the eyes.

In ancient Hawaii, aama was a sacred food for priests, but the crab had to be whole with no legs missing. Hawaiians also used aama to treat illnesses, and as sacrificial animals to persuade the gods to answer a request. Today, people use the crabs for both bait and food.

I love seeing the busy little aama scurrying around the rocks near my boat, but not everyone appreciates them. Once, while I fumbled with my gate key, a mainland friend gripped my arm. "Hurry," she said.


She looked down at the rocks and made a face.

"The rock crabs? They can't hurt you."


"They're called aama," I told her, as their dark bodies scurried over the rocks.

"Thank god," she breathed. "I thought they were tarantulas."



Marine biologist Susan Scott writes the newspaper column, "Ocean Watch",
for the Honolulu Star-Bulletin,