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Giant Clams


Ajikē Sashimi
Photo: TARUMI Kengo

The first time anyone sees any member of the giant clam family, they’re bound to think, “What a huge shell!” There are some giant clam shells in souvenir shops that are so big one person alone probably couldn’t lift them. 

But there’s one species of giant clam unlike any other. That is the himejako, the boring clam, which you can sometimes spot if you walk along a dried coral reef. The clam burrows its entire body into the hard body of the coral, leaving only the opening exposed, and if you peer inside that opening, you’ll be surprised. Inside the mouth of the boring clam, you’ll sometimes glimpse green-tinged fragments of the Aurora Borealis shining bright, or if you’re particularly lucky, a vision of the universe in its infancy just after the Big Bang, a gleaming, bewitching blue-purple undulation. That is the boring clam in a nutshell—a shell containing the boundless universe within. This is why I’m quietly in awe of the boring clam.

The true form of the universe within the boring clam is a vast quantity of symbiotic algae living in the clam’s water-vascular system—the algae’s cells form a lens to take in light for photosynthesis and the cells adjust the irises of those lenses to control the amount of light reaching inside, which in turn gives off that mysterious glimmer. Or at least that’s what people giving a scientific explanation say. But they don’t comprehend the truth of the boring clam’s form.

Long ago, you’d see these clams in abundance, forming some far-off galaxy, but they’ve been overfished for their delicious meat, and the clam haul has dropped off precipitously. At the Naha public market in December of 1991, one hundred grams of boring clam meat cost one thousand yen (about $10 US). There are laws prohibiting the capture of clams measuring less than eight centimeters, and there have also been attempts to cultivate populations by releasing clam fry, but neither of these has had a visible effect. Okinawa used to produce a lot of ajikēgarasu—a dish made from salted, fermented boring clam—but that cuisine is becoming more and more rare. In addition to the boring clam, there are other species of giant clam which live near Okinawa: the fluted giant clam; the smooth giant clam; the maxima clam; the horse hoof clam; and tridacna gigas, the true giant clam. In and around Okinawa giant clams are generally called ajikē, and in the Yaeyama Archipelago they’re called gīra, but strictly speaking, there’s not much difference between the two. The giant clam shells you might find around or next to gateposts or entryways are not simply decorations but in fact proper talismans against evil spirits. 

All things considered, the coral reefs that have lost those mysterious chasms which allowed us to glimpse the universe at our feet seem unbearably lonely.