You might see barnacles in a different light once you get to know them

SHARON WOOTTON

Originally published July 31, 2001

It's funny how perspective can change over the years.

Barnacles once meant hours scraping thousands off rowboat bottoms and getting my net caught on an encrusted piling, allowing the crab to escape.

Now I'm an ardent admirer of acorn barnacles.

After all, here's this tiny, swimming, shrimplike organism that decides to settle down, stands on its head on a solid surface, secretes a glue that researchers have been trying to duplicate for decades, builds a rocklike fortress and kicks food into its mouth with its legs.

The tiny barnacle is dingy, light-gray and volcano shaped, although occasionally you'll find column-shaped barnacles. That's not another species but a response to overcrowding.

Long before high-rises, barnacles knew that if you couldn't spread out, then build up. The architecture of the shell changes depending on how the barnacle deposits the calcium carbonate.

There are about 1,500 barnacle species worldwide, most of them found in the high-tide zone if they haven't hitched a ride with a whale. I've seen them on driftwood, crabs, buoys and sharks. Thousands of pounds of barnacles can accumulate on the hulls of freighters, creating so much drag that fuel consumption increases 30 percent to 40 percent.

Balanus glandula is the dominant life form in the upper limit of the high tides. When tightly closed, the six-plated, sharp-edged shell protects the soft parts inside against predators (sea stars, whelks, gulls), pounding waves and drying out. Barnacles can survive without water for several days at a time.

The barnacle eats in, fed by plankton floating by. Its plates open, it stretches reddish feathery legs (cirri) to sweep the water and draw in food, closes during delivery to the mouth and then opens for the next sweep.

Barnacles feed primarily in the spring and autumn when the levels of plankton are highest, then just nibble during the other seasons, drawing on their own food reserves.

Barnacles have s-e-x. Being hermaphrodites, each barnacle has male and female sex organs, solving the immobility problem, although depositing sperm can get a little complicated with shells opening and closing and neighbors giving and receiving at the same time.

Parents hold fertilized eggs until larvae hatch, then send out about 30,000 one-eyed, six-legged larvae during winter and spring. Five transformations later, survivors have three eyes and an urge to nest.

Adults give off a chemical that assists the young ones in finding other barnacles (it's the sex thing). The shrimp-like creature anchors itself with an adhesive secreted from glands on its first antennae, gluing its head to the surface, and begins building a shell. It also loses its eyes.

The glue (exocytosis) hardens quickly and holds up under extreme pressure and temperatures, as in hundreds of degrees above and below zero. It's hundreds of times stronger than the strongest commercial epoxy.

In order to grow, barnacles molt. Imagine taking off your long johns while inside a sleeping bag. The interior being sheds its exoskeleton (long johns), not the calcium carbonate fortress (sleeping bag), which, like your skull, has plates that grow in the margins.

All of which is to say, a little knowledge can alter one's perspective.

Sharon Wootton is a free-lance writer from the San Juan Islands. She can be reached at songandword@rockisland.com or by telephone at 360-468-3964.

The Olympian Copyright 2001

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