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Ocean Watch Susan Scott |
Sometimes,
the barnacles
just have to goI love windy days because I like to look for junk that blows in from the ocean. This week on Kailua Beach, I found a plastic float the size of a soccer ball. The sphere had loops on each side where ears might be, and a slash across the front like a grin.
To the dismay of the ghost crabs that surrounded the black float, I picked it up and took it home.
"Very nice," said my sister, an artistic soul who can see the sublime in a rusty rat trap. "What are those things stuck on it?"
"Goose barnacles. The crabs were eating them." I tapped a barnacle. It closed its shells and recoiled from my touch.
"Oh, no, they're alive!" this animal lover said.
I explained that the only way to save them involved driving to the Leeward side of the island and launching them in a place free of obstructions. And then, even if they made it back to sea, their home ball would sometime, somewhere, wash in again.
"Still," she said, "they're living animals."
And so began another goose barnacle guilt trip.
It's nearly impossible to find anything that's been in the open ocean for even a short time without goose barnacles growing on it.
Once, while sailing from Costa Rica to Hilo, the tradewinds turned off as if a fuse had blown. Completely becalmed, my partner and I dropped the sails, jumped in and looked at our hull. Four weeks earlier, we'd scraped it clean. Now an entire city of goose barnacles squatted there.
How those microscopic creatures caught hold of a smooth surface coated with anti-fouling paint as it crashed through 15-foot waves in 25-knot winds was beyond us.
Finding a home, however, is a life-or-death matter for a baby barnacle. It can attach itself temporarily to a site, but it doesn't have long to decide if it likes the neighborhood. At this pioneering stage, barnacles can't eat.
Once they've cemented themselves down, there's no turning back. The animal spends the rest of its life glued to that spot.
Although they're crustaceans rather than mollusks, as biologists once thought, goose barnacles look like plants from the Little Shop of Horrors. Each has a brown, muscular stem tipped with white, moveable plates that resemble a jointed, pointed clamshell.
Here in tropical waters, goose barnacles grow 3 or 4 inches long. In colder waters they can be 30 inches long.
When undisturbed, the barnacle opens its shells and extends wispy, brown appendages. These "fingers" pulse rhythmically, filtering the water for plankton. When alarmed, the limbs withdraw and the shells snap shut.
If given a chance, these little carnivores will gorge themselves. In one lab experiment, a goose barnacle choked down a brine shrimp bigger than itself while at the same time clutching seven planktonic crustaceans called copepods.
Beneath our boat, wearing masks and snorkels, we watched the barnacles feed gracefully. Then, with heavy hearts, we scraped them off and they fell to their deaths.
Back on my lanai, I stared at the squirming creatures wondering where we animal lovers should draw the line in our respect for life.
My line went around my car. No way was I driving a bunch of barnacles around this island. Besides, I really wanted their ball.
After my sister left, I killed the lot with vinegar. Sure, I felt guilty. But it's nothing new.
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Marine science writer Susan Scott can be reached at http://www.susanscott.net.