On Tuesday, hundreds of presumably responsible adults will knock off work early, head out to Anthony's HomePort on Shilshole, and spend the rest of the day and most of the evening—and a sizable chunk of cash—for the privilege of eating an unlimited number of live raw oysters, watching local celebrities eat live raw oysters, watching people gouge live oysters out of their shells against the clock, and even dress up like oysters or in oysters. Considering that a healthy majority of people find the whole idea of chewing up and swallowing a cold, slippery living thing deeply repellent, this celebration devoted mainly to doing just that requires some explanation. This is the 15th annual Anthony's Oyster Olympics, and those 15 years have been, on the whole, boom years for the Northwest oyster industry. While old established oyster fisheries like the ones in Chesapeake Bay and South Carolina have dwindled to one-twentieth or less than their former size, oyster raising on Puget Sound and in the protected estuaries of the state's Pacific coast has grown mightily, despite disease and pollution problems of our own. Production is at the highest it's been since Euroamerican settlers descended on California in search of gold. Oysters and humans hereabouts afford an unusually vivid example of how two or more species co-evolve toward ecological balance. When white people arrived on the Pacific coast, the only oyster they found there was the tiny, slow-growing native species, known today as the Olympia oyster, though its habitat extended from the Queen Charlottes to Baja. Native sources of protein were few in Gold Rush country, and oysters were consumed by the billions, first in San Francisco Bay, then down and up the coast until, by 1900, there weren't enough left even in Puget Sound to satisfy demand. Some oystermen began to experiment with farming the native species. (Taylor Shellfish, sponsor of the Oyster Olympics, has been doing it for more than a hundred years.) Others tried raising the Atlantic species (pretty much a bust) or the European variety (even more so). But they hit the jackpot with the Japanese species known to science by the unflattering name Crassostrea gigas ("huge gross oyster") and to the trade by the somewhat misleading name "Pacific oyster." Pacifics grew so fast and so prolifically in Northwest waters that they quickly spread beyond farms to every suitable tidal habitat: a rare example of an invasive species that also happens to be good for something. Pacifics grow almost too well. If not harvested in their yearling prime, they can grow to the dimensions of a weathered gum boot, unappetizing to even the most indiscriminating oyster eater. So even as Pacifics were farmed far and wide (Taylor alone has eight beds in Washington), the search went on for something a little more dainty and attractive. Such an oyster was found growing naturally in the sheltered bays of the southern-most Japanese island of Kyushu near the city of Kumamoto. At first believed to be just another variety of Pacific oyster (oysters are greatly affected in appearance and taste by their microenvironment), the Kumamoto is now believed to be a separate species (Crassostrea sikemea). It certainly looks different, nestling pale white in its deep-cupped fluted shell. Oyster aficionados say it tastes different, too—sweet, buttery, and fresh. In fact, it's become the gourmet oyster of choice, even though the once-rare native oyster has recently been making a modest commercial comeback. During the gung-ho dot-com days, oysters, along with other demonstratively upscale foods, experienced a major boom, with "raw bars" becoming de rigueur at restaurants seeking the elusive yuppie seal of approval. Curiously, they've only become more prevalent since the dot-com smash, with some spots offering a dozen or more named varieties and as much attention to sourcing as a wine-steward devotes to his cellarage. How much of our oystermania is pure fashion, how much an opportunity for conspicuous consumption? Oysters, once so numerous that an oyster sandwich was without irony called a "poor boy," are now pricey at best, with the tiny native Olympia commanding prices ounce for ounce rivaling those of foie gras and caviar. Trend or not, there's no sign so far of a drop in oyster eating. Sushi, once a refined rarity, now is almost a commodity. With food sophistication constantly expanding but fewer than a third of consumers currently willing to let a raw bivalve pass their lips, the market for oysters seems to be signaling a "buy." email@example.com Anthony's Oyster Olympics: Anthony's HomePort at Shilshole Bay, 6135 Seaview Ave. N.W., 206-783-0780, BALLARD; 3–8 p.m. Tues., March 30. $85 (purchase tickets in advance from Puget Soundkeeper Alliance, 206-297-70020).