This shrimp is the exact length of a shaku, or Japanese foot. That’s how they came up with this form of measurement. They measured the length of this shrimp and it was the length of a Japanese foot which they deemed the shaku. It’s equal to 30.3cm, very close to one imperial foot.
How is shaku, the Japanese foot, pronounced by Shaq (しゃく) in Japanese? Why Shaq pronounces it shaku. It’s pronounced shaku in both English and Japanese.