The Opihi Shellfish Story
What’s going on underneath those shells? From gastronomy to conservation to evolutionary biology, we pry the secrets out of these little limpets.
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Calantoc is well aware of the dangers of his trade. He knows pickers who have drowned, and he’s been in some scary situations himself. “I’ve had waves knock me off into the water before,” he says. “It’s spooky getting swept into the ocean.” The key to survival is not to panic if you get washed off the rocks, he says, and to try to minimize the risk of that happening in the first place. “I don’t go when there’s stupid crazy lightning and thunder and 10- to 15-foot waves,” he says. “You gotta know your limits.”
The Opihi as Snail
Opihi are limpets, part of a broad category of marine snail characterized by conical shells. Limpets like opihi have gills, a powerful suction-cup-like “foot,” something resembling a heart, and a mouth at the end of a protractible mouth tube. They don’t have actual eyes, but they do have eyespots, which are sensitive to sunlight and shadows. Their little worlds are dominated by darkness and light. If the shadow of an opihi picker falls on one, it clamps down with all its might and the picker may as well move on to the next rock.
Limpets are found around the planet, but the three species of Hawaiian limpet are endemic, meaning they’re found nowhere but Hawaii, unless a Hawaiian food lover arranges for their travel. The most common opihi is the blackfoot, or opihi makaiauli, which lives on the wet rocks above the brunt of the surf. The kneecap opihi, also known as the koele, lives underwater from the low-tide line down to 10 feet. The yellowfoot, or opihi alinalina, lives in between, where the rocks get pounded hardest by waves. The yellowfoot is preferred by opihi aficionados. The blackfoot, which are the easiest to pick, are called “the lazy man’s opihi.” The kneecap grows the largest, getting up to four inches across, which is actually more like a knee pad.
It is widely believed that a fourth species of opihi can be found mainly in the Northwestern Hawaiian Islands, with a thicker and pointier shell than the others, but opihi science has learned otherwise. “There is no fourth species,” says Chris Bird, a biologist who has been unraveling the mysteries of the opihi genome in his Coconut Island laboratory at the Hawaii Institute of Marine Biology. In a soon-to-be-published paper, Bird reports that, while this so-called fourth species looks different from the other species, it is genetically identical to the opihi makaiauli and the opihi alinalina. In other words, it’s the blackfoot and the yellowfoot in disguise. “What we’ve thought was a fourth species doesn’t really exist,” says Bird. “We need to take it off the books.”
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