National Geographic : 1973 Nov
Also, if we release a ship from a battle zone for cleaning, we reduce our firepower. "Then, too, friction from hitchhiking bar nacles 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 mil lion 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 FLIPSCHULKE,BLACKSTAR since Jurassic times. Fossils from that period show barnacles still attached to surfaces they settled on some 150 million years ago. How ever, these tiny troublemakers have been around far longer than that. Paleontologists trace their history back 400 million years. Darwin Intrigued by the Crustaceans 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. Al most 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 cen turies. 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 esti mates 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, re mains forever attached to one spot. Part of the explanation is that the majority *Alan Villiers chronicled this nearly five-year-long voyage in the October 1969 NATIONAL GEOGRAPHIC. Nose full of barnacles, a gray whale stands on its tail. Scientists believe that the mam mals scrape themselves against the sea bot tom to get rid of the tenacious pests.