(The following passage is the introduction to an article published by an American writer in 2010.) On the night of December 10, 1999, the Philippine island of Luzon, home to the capital, Manila, and some 40 million people, abruptly lost power, sparking fears that a long-rumored military coup d’état was underway. Malls full of Christmas shoppers plunged into darkness. Holiday parties ground to a halt. President Joseph Estrada, meeting with senators at the time, endured a tense ten minutes before a generator restored the lights, while the public remained in the dark until the cause of the crisis was announced, and dealt with, the next day. Disgruntled generals had not engineered the blackout. It was wrought by jellyfish. Some 50 dump trucks’ worth had been sucked into the cooling pipes of a coal-fired power plant, causing a cascading power failure. “Here we are at the dawn of a new millennium, in the age of cyberspace,” fumed an editorial in the Philippine Star, “and we are at the mercy of jellyfish.”

A decade later, the predicament seems only to have worsened. All around the world, jellyfish are behaving badly—reproducing in astonishing numbers and congregating where they’ve supposedly never been seen before. Jellyfish have halted seafloor diamond mining off the coast of Namibia by gumming up sediment-removal systems. Jellies scarf so much food in the Caspian Sea they’re contributing to the commercial extinction of beluga sturgeon—the source of fine caviar. In 2007, mauve stinger jellyfish stung and asphyxiated more than 100,000 farmed salmon off the coast of Ireland as aquaculturists* on a boat watched in horror. The jelly swarm reportedly was 35 feet deep and covered ten square miles.

Nightmarish accounts of “Jellyfish Gone Wild,” as a 2008 National Science Foundation report called the phenomenon, stretch from the fjords of Norway to the resorts of Thailand. By clogging cooling equipment, jellies have shut down nuclear power plants in several countries; they partially disabled the aircraft carrier USS Ronald Reagan four years ago. In 2005, jellies struck the Philippines again, this time incapacitating 127 police officers who had waded chest-deep in seawater during a counterterrorism exercise, apparently oblivious to the more imminent threat. (Dozens were hospitalized.) This past fall, a ten-ton fishing trawler off the coast of Japan capsized and sank while hauling in a netful of 450-pound Nomura’s jellies.

The sensation of getting stung ranges from a twinge to tingling to savage agony. Victims include Hudson River triathletes, Ironmen in Australia and kite surfers in Costa Rica. In summertime so many jellies mob the waters of the Mediterranean Sea that it can appear to be blistering, and many bathers’ bodies don’t look much different: in 2006, the Spanish Red Cross treated 19,000 stung swimmers along the Costa Brava. Contact with the deadliest type, a box jellyfish native to northern Australian waters, can stop a person’s heart in three minutes. Jellyfish kill between 20 and 40 people a year in the Philippines alone.

The news media have tried out various names for this new plague: “the jellyfish typhoon,” “the rise of slime,” “the spineless menace.” Nobody knows exactly what’s behind it, but there’s a queasy sense among scientists that jellyfish just might be avengers from the deep, repaying all the insults we’ve heaped on the world’s oceans.

Copyright 2010 Smithsonian Institution. Reprinted with permission from Smithsonian Enterprises. All rights reserved. Reproduction in any medium is strictly prohibited without permission from Smithsonian Institution.
In the third sentence of the fourth paragraph, the author mentions the number of swimmers treated by the Spanish Red Cross primarily to