Akagai (Ark Shell) Sushi

Akagai / Blood clam / Ark shell

Shellfish

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Arcoida, Arcidae, genus Scapharca

It lives in the shallow sandy-muddy areas of shallows, inner bays, and tidal flats from southern Hokkaido to Kyushu, and from the Russian Maritime Province to the East China Sea. As its name suggests, both its flesh and its blood are red. It was once caught in large quantities in Tokyo Bay as well and is a representative of Edo-mae sushi, but at present imports from Korea and China account for the majority.

The ark shell is a bivalve that lives in the shallow sandy mud of coastal waters in Japan, the Korean Peninsula, China, and the Russian Far East. Long ago it was caught in large quantities in Japan too, but it sharply declined along with the pollution of inner bays and became a luxury ingredient, so most of the ark shells in distribution are now imports from China and Korea. The ark shells served at conveyor-belt sushi are often the related species Scapharca satowi (satogai) or Scapharca subcrenata (sarubo). Domestic ark shells are few, but they are caught in Sanriku, Nagasaki, Mie, Aichi, and elsewhere. In particular, the ark shells of Yuriage in Natori City, Miyagi Prefecture, are highly prized for the thickness of their flesh and the quality of their aroma, earning a reputation as the best in Japan. Because those carrying eggs have leaner flesh and a poorer flavor, the season is said to be around autumn, after the summer spawning, when the savoriness increases. Ak shell sushi is a luxury sushi topping now, but in the Edo period it was caught in large quantities in Tokyo Bay, so it was a representative of the common, everyday sushi toppings of Edo-mae sushi. The stronger the red color, the better the quality is said to be. It is characterized by a seashore aroma, a crunchy bite, and a faint sweetness and bitterness, and a fresh ark shell is filled with a refreshing aroma of the shore.

The Addictive Mantle Sushi of the Ark Shell

The mantle (himo) of the ark shell is unusual among shellfish in that the mantle is sometimes said to be tastier than the body. "Himo-kyu," in which the mantle is rolled together with cucumber, is also a popular sushi roll known to those in the know. Because the amount of mantle obtained from a single ark shell is small and precious, it is also said to be a sushi topping for one's valued regular customers. It is a gem, and many people become addicted to its bite, which is even crunchier than the main body.

In the Edo period, ark shells were caught in large quantities even in Tokyo Bay

The Goddess of the Ark Shell

When you open an ark shell, a red liquid spurts out, and the identity of that liquid is the ark shell's blood. Bivalves of the family Arcidae, including the ark shell, contain a great deal of hemoglobin in their blood, which appears red when it binds with iron, and its components are said to be close to those of humans.
With hair growing on its shell, the ark shell almost makes you wonder whether a human long ago turned into a shellfish, and in fact a goddess of the ark shell, Kisagai-hime, appears in Japanese mythology.
Kisagai-hime plays an active role as a goddess of healing, bringing dead gods back to life and curing injuries, and even today she is revered and worshipped as a deity of longevity, health, and recovery from illness.