【Reading】とこぶし

【English Name】Tokobushi abalone

The tokobushi (Sulculus diversicolor, a small abalone) is a kind of sea snail belonging to the family Haliotidae, closely related to the awabi (abalone). Recognized as a subspecies endemic to Japan, its main habitat is rocky-reef waters from southern Hokkaido to northern Kyushu. It lives from the shallows to depths around 10 m and the intertidal zone, with Nagasaki given as the type locality.

The shell grows to about 7 cm long and 5 cm wide, but is more than a size smaller than an adult awabi. Because its appearance closely resembles a juvenile awabi, it is easily confused, but the number of respiratory pores (tremata) lined along the shell face is the identification point. Whereas the awabi has 4-5, the tokobushi has 6-8 pores, and the raised rims around the pores are more subdued than the awabi's. The outer shell is blackish-brown, and the inner surface spreads with a vivid pearly luster.

The origin of the name, as its kanji writing 床臥 ("lying on a bed") indicates, is said to stem from its ecology of settling as if crouched flat on bedrock. The breeding season is roughly September to October, and waves after the passage of typhoons are thought to trigger spawning and milt release.

As a foodstuff it is processed by salt-steaming, simmering, and canning. Because the flesh is small, it is often simmered whole. In Yamanashi (Koshu), "nigai" (simmered shellfish)—tokobushi brought from the Suruga Bay area and simmered in soy sauce—has long been enjoyed as a local flavor.