【Reading】きたむらさきSea Urchin

【English Name】Northern Sea Urchin

Kita-murasaki-uni is a cold-water sea urchin classified in the family Strongylocentrotidae, and one of the representative species widely eaten in Japan. It is written in kanji as 北紫海胆.

The shell is about 6-7 cm in diameter, and the spines are about 2-3 cm long, showing colors such as dark green, dark purple, and dark brown. It resembles the murasaki-uni, which is common in the south, but this species prefers cold waters and is said to find survival difficult when temperatures exceed 26-30 degrees C.

On the Pacific side it is distributed north of Sagami Bay, and on the Sea of Japan side from north of Shimane Prefecture to Hokkaido, with its inhabitation also confirmed in coastal areas of the Korean Peninsula and northern China. It lives on reefs from the intertidal zone down to depths of about 180 m, feeding on seaweed and organic matter. Its lifespan is roughly 14-15 years.

The edible part is the gonads (ovaries and testes), and Hokkaido-grown urchin develops good roe mainly around June to August. The spawning period of September to October is a closed season in many areas. Eaten raw is the mainstream, but there are also processed products such as steamed urchin and salted urchin (shio-uni), and in Fukushima Prefecture grilled urchin in the shell (uni no kaiyaki) is enjoyed as a specialty.

In the market there is a custom of distinguishing the bafun-uni as red and this species as white. In recent years, as an attempt at cultivation that doubles as a measure against isoyake (sea desertification / barren grounds), efforts to use discarded vegetables as feed are advancing in various places.