By Jan TenBruggencate
There are three species of edible limpets, called ‘opihi in Hawai‘i, that crawl the shoreline boulders.
Each is distinct, and lives at a different zone of the coastline — from several feet below the surface to the highest wash of the waves.
They are all unique to the Hawaiian Islands, and are so prized that all are at risk of overharvesting.
And all three are believed to have evolved from a single ancestral limpet that arrived in the Hawaiian archipelago 3 to 7 million years ago. The larvae may have been carried on the ocean currents from the area now occupied by Japan, researchers say.
Having evolved into unique species here, they are true indigenous natives of the Islands. All three are in the genus Cellana.
Each has the classic cone-shaped shell, with raised ridges radiating from a central peak.
‘Opihi, to some folks are an acquired taste in local cuisine, but to old-timers, they are prized at any gathering. And costly to buy, if you can find them. They’re a little rubbery, a little crunchy, and the flavor speaks of the sea.
Collecting them can be dangerous because you’re right in the breaking wave zone on rocky shores.
The biggest one is generally the one found effectively always under water, often as deep as 10 or so feet. It is the ko‘ele, known to science as Cellana talcosa. Some folks call it the kneecap ‘opihi, because it can be as big as your kneecap and its shell is very thick.
If you slide a butterknife under its foot and lift it off the rock, the foot — the muscle on which it travels — is gray in color, but that’s not a perfect distinguishing factor. Occasionally, the foot of a ko‘ele can be yellow.
While it is the biggest of the ‘opihi, the ko‘ele is not considered the best for eating. Still, it is heavily harvested and is reported nearly gone from O‘ahu
The crème-de-la-crème of ‘opihi would be the next one up the shoreline.
This is the one that takes the most surf pounding, the ‘alinalina or Cellana sandwicensis. Its English nickname is yellowfoot, since the foot is a shade of yellow. It’s the one most ‘opihi pickers go for—and the most dangerous to collect since you generally can’t collect them without yourself being in the surf’s blast zone.
The third `opihi is found higher on the rocks, in areas that are occasionally splashed by the waves, but at low tides may bake in the sun for long hours. It is the makaiauli or Cellana exarata.
It is smaller than the ko‘ele, but also has a gray foot. It can be distinguished by its high position on the rocks and by the appearance of a greenish rim around its foot.
All three are vegetarians, using a rasping tongue to feed on marine algae found on the rocks.
A fourth ‘opihi is not closely related to the edibles. It is sometimes called the small false ‘opihi, ‘opihi ‘awa, or Siphonaria normalis.
- Jan TenBruggencate is a Kaua‘i based writer and communications consultant.