A coastal animal of East and Southeast Asia with a hard shell and long tail. It lays eggs on sandy shores, and young animals grow on tidal flats.
A crescent-shaped shield covers the front of its body. Spines line the sides of the rear section, followed by a long pointed tail.
At Kasaoka, pairs approach sandy shores on summer nights at high tides, with the male attached to the female. Females dig into the sand and lay successive batches of eggs while moving along the shore.
At Kasaoka Horseshoe Crab Museum, newly hatched first-instar larvae swam in water and gathered towards the brighter side of a container.
Young animals grow through repeated moults on tidal flats and move into deeper water as they get larger.
It eats bottom-dwelling animals such as polychaete worms and clams.
In a 2019 experiment at Tsuyazaki Cove, Fukuoka, eggs from one breeding pair were moved to eight points at different shore elevations, with 100 eggs at each point. Among the four regularly checked points, only a middle-elevation point retained live eggs at the final inspection on 21 August.
An extinction-risk assessment has not been added yet.
In Kasaoka Bay, large-scale reclamation and the accompanying deterioration in water quality threatened the population. Conserving sandy shores, tidal flats and clean seawater is a protection priority.