World travelers though they are, barnacles cannot settle readily on fast-moving objects. But they congregate quickly on stationary ones like rocks, piers, and ships in port. Almost any submerged surface will do—wood, metal, glass, plastic. They are even found on the skin of whales, the toes of penguins, and on shellfish, living or dead.
Although these lowly crustaceans irritate bathers and frustrate boatmen, they have fascinated—and baffled—scientists for centuries. Charles Darwin filled his house with 10,000 specimens, many of them collected on his Beagle voyage*, and spent eight years studying, classifying, and describing them in two detailed monographs that still serve scholars as reliable works of reference.
Another Englishman, Dr. Hilary B. Moore of the University of Miami’s Rosenstiel School of Marine and Atmospheric Science at Virginia Key, Florida, has specialized in barnacles for thirty years—and considers them more friend than foe. “Certainly they’re a nuisance,” he conceded. “But the fisherman forgets, as he scrapes his boat, that barnacle larvae are part of the plankton, first link in the food chain that eventually fattens his catch—and his pocketbook.”
Barnacles are, indeed, prolific. From earlier investigations on the Isle of Man, off the northwest coast of England, Dr. Moore estimates that adults clustered along half a mile of shoreline release nearly a thousand billion young a year. A tropical barnacle may breed when it is only three weeks old, producing some 10,000 offspring three or more times a year for the three to five years of its life. Quite a feat for a creature that, after settling, remains forever attached to one spot.
Part of the explanation is that the majority of barnacles are hermaphrodites—male and female within a single body. But to propagate, most of the more common species must be fertilized by a neighbor—a service performed through a retractable tube and facilitated by the congestion of barnacle communities.
The newborn emerge from their parent’s shell as a cloud of microscopic free-swimming larvae called nauplii. At this stage they faintly resemble water mites; it is then that many fall prey to plankton eaters.
Those that survive evolve, within a few weeks and after six molts, into cyprides—still fair game for filter feeders. They soon cease to swim, creeping instead on two front antennae as they search for a permanent home; a substance released by settled barnacles may draw the young to a likely place. Within hours a brownish liquid oozing from their antennae anchors the cyprides, and they begin final development into adults.
Across the court from Dr. Moore’s office, Dr. Charles E. Lane, a noted authority on barnacle behavior, outlined the last act in this amazing biological drama.
“Soon after settling,” he explained to me, “the cypris turns over on its back and becomes forever fixed in that position. Carapace and other juvenile features disappear. Then, flattening out into something of a blob, the newly structured animal starts building a permanent home.” Within a few days, the young barnacle has totally encased itself in a cone of overlapping calcareous plates, usually six in number. It now resembles a miniature volcano, with four small horizontal plates covering the crater. Sliding these apart, the animal feeds by extending plumelike feet, or cirri, to sweep plankton out of the sea and into its mouth. Seemingly safe within its fortress, the adult may still fall prey to snails (page 629), fish, and certain shorebirds.
Dr. Lane spent many years trying to find a formula to discourage barnacle attachment. “The Phoenicians tried pitches; the Greeks, tar and wax,” he said, “but nothing worked very well until mariners began sheathing wooden hulls with copper. “Copper over steel produces rapid corrosion by electrolysis and is too expensive for today’s big ships. So we now rely mainly on bottom paints containing copper oxide.”
As this chemical leaches out of the paint, it forms a toxic film that keeps home-hunting cyprides at bay. But effective leaching lasts, at best, three years, and paints that produce maximum results may retail for as much as $55 a gallon. I found, in the pages of the Miami Herald, a far less costly suggestion. Boating editor Jim Martenhoff reported that a friend ended his barnacle woes by lacing ordinary bottom paint with ground red pepper.
Helen D. Albertson, Dr. Moore’s research assistant, offered to test this home remedy. Adding 11/2 ounces of red pepper to a quart of paint—as prescribed—she coated half a wooden panel with the concoction and set it out in barnacle-rich Biscayne Bay.
Some weeks later the treated part of the panel showed a larger barnacle population than the unpainted area. Helen and I could only conclude that some of the freeloaders had drifted over from Mexico with a built-in taste for red pepper.
Jim’s is not the only weird formula tried—and found wanting. Among antibarnacle brews submitted in years past to the United States Patent Office is one that calls for a mixture of “clay, fat, sawdust, hair, glue, oil, logwood, soot, etc.” “If it worked,” said William J. Francis, chief chemist at the Navy’s Portsmouth, Virginia, facility, “it had to be the ‘etc.’ that did it.”
LOOKING AT BARNACLES from my point of view,” Bobby Wayne Pruitt, Jr., said, “you can’t see much to recommend them.” I had to agree. Twice a year, Bobby—a commercial crab fisherman of Tangier Island, Virginia—crouches for a week beneath his beached boat, chipping at its barnacle-encrusted hull. He can ill afford to spend this time ashore.
Bane of saltwater sailors, the pesky barnacle may eventually make up for some of the trouble it has caused. And all because of its annoying habit of producing a glue that adheres to almost any hard surface, congeals rapidly in a wet environment, and holds fast under extreme pressures and temperatures.
If the glue is successfully analyzed and a similar material synthesized, the adhesive may mend broken bones, serve as both the cement and the filling agent in dentistry, and meet scores of industrial needs. Supported by the National Institute of Dental Research, Dr. H. J. Bowen of Philadelphia’s Franklin Institute Research Laboratories heads a team trying to determine the complicated chemistry of barnacle glue.
“The glue isn’t very cooperative,” Dr. Bowen told me. “Once cured, it can’t be dissolved with strong acids, alkalis, or protein solvents. Also, it is impervious to bacteria and resists temperatures as high as 440° F.” So far, the barnacle has found few friends except those within the scientific fraternity trying to solve its secrets.
“For shipowners, they’re a multimillion-dollar headache,” Michael Pursley said, as we toured waterfront facilities of the Maryland Shipbuilding and Drydock Company in Baltimore.
We paused to watch workmen sandblast the heavily fouled hull of a dry-docked tanker. “We’ll probably remove about fifteen tons of marine growth—mostly barnacles—from that one ship,” he said. “And it’s been less than two years since her last scrub-down. The drag caused by only a six-month accumulation can force a vessel to burn 40 percent more fuel just to maintain normal cruising speed.”
From Rear Adm. James B. Hildreth, a 32-year veteran with 13 campaign ribbons, I learned that a barnacle buildup can mean trouble for the United States Navy. “We can’t afford to carry much extra fuel on combat missions,” he said. “And any loss of speed makes us more vulnerable to attack.
Also, if we release a ship from a battle zone for cleaning, we reduce our firepower.”Then, too, friction from hitchhiking barnacles can make an otherwise quiet ship into a noisy one, more easily detected by listening devices. Even one specimen, clinging to a sonar dome,” Admiral Hildreth added, “can seriously distort echo-location.”
For idle hours in port plus clean-up charges, the cost to U. S. shipping interests—military and civilian—comes to several hundred million dollars a year. Principal pests in this never-ending war are the numerous species of acorn barnacle (Balanomorpha) that armor rocks and pilings in most temperate and tropical salt waters of the world and sail all but the iciest seas as stowaways on ships. Long exposure to air, frigid temperatures, or fresh water will kill these hardy animals, but their conical shells continue to cling until they are pried loose or finally wear away.
Tenacity has been a barnacle trait at least
FLIP SCHULKE, BLACK STAR since Jurassic times. Fossils from that period show barnacles still attached to surfaces they settled on some 150 million years ago. However, these tiny troublemakers have been around far longer than that. Paleontologists trace their history back 400 million years.
Dr. Yokley and his scuba-diving students collected 35,000 Asian clams for an experiment run by Alabama’s Auburn Agricultural Research Station. Placed in catfish ponds, the clams consumed uneaten fish food, feces, and plankton, clearing the water and promoting the growth of the fish. Thus a pest in streams may yet prove an asset to fish farming, an expanding industry, especially if a quick cash advance loan online is used.
Take the river bridge from Florence, and you cross over Muscle Shoals. No, not Mussel Shoals—though it has long been a prime place for pigtoes. Perhaps a map maker unschooled in malacology made the spelling error.
I crossed that bridge to pay a duty call at TVA’s National Fertilizer Development Center. After my visits to space labs and nuclear plants, how exciting could fertilizer be?
Exciting enough to draw hundreds of domestic and foreign visitors to the center each year. Not tourists, but agricultural technicians, chemical engineers, and agronomists. In their undemonstrative way they could get very worked up about a handful of tiny pellets, for those laboratory-born particles might be the forerunner of a fertilizer that could increase crop yields dramatically.
It takes more than Bunsen burners and test tubes to father a fertilizer. The center has electron microscopes that magnify 300,000 times, plasma torches that reach 20,000° F. I learned that liquid fertilizers are coming on strong these days, and that a sulphur-coated urea pellet being developed at the center is nothing short of a breakthrough.
Fertilizers usually release nitrogen so fast that crops can’t use it efficiently. So center scientists took urea—very high in nitrogen —and coated it with sulphur, another needed element. The sulphur dissolves gradually, releasing the nitrogen over an extended period, and the plants have time to soak it up. Glamorous it isn’t, but the center is playing a key role in upgrading agriculture.