Using a fence designed to obstruct the movement of the shortspined sea urchin, Strongylocentrotus intermedius, and the northem sea urchin, Strongylocentrotus intermedius, the characteristics of their behaviors on different
substrates, and their behavior on horizontal and vertical plates were observed.
Five kinds of substrates were used (i.e. acrylic, cloth, sponge, and 2 kinds of net). On these substrates, their
moving force and speed were measured. Using a video camera, sea urchins positioned on a horizontal plate or at
one side of a vertical plate were observed moving across the plates.
For both species, the moving force and speed on the acrylic board were highest, i. e. 270 gf and 2.9 cm/s
for the short-spined sea urchin, and 417 gf and 5.0 cm/s for the northem sea urchin. The lowest values for the
short spined sea urchin were 27 gf and 0.6 cm/s on sponge, while the lowest for the northem sea urchin were
45 gf on sponge and 2.5 cm/s on net. The sea urchins could move easily across the plates. After observing the
moving behavior of sea urchins, it was considered that the kinds of substrates and the urchin's position on a plate
are not factors which obstruct the sea urchin movement.