Abstract
In order to trace a movement of a spiny lobster in an experimental tank under dark condition, a two-dimensional tracking device was designed, and its outline was reported in the previous paper(Koike et al., 1996). We found a defect that water level change of several mm produce error of about 10 cm in lobster position in this device. To minimize this error, the lobster cage is completely submerged except its supporting poles. However, we need to set a ceiling net and a slippery wall to the lobster cage. These increases drug force of the cage, and results swing of the cage due to flow inside the tank. The end shape of the water supply pipe was reformed so as that the flow in the tank is slow and smooth enough to avoid significant error in determination of lobster position.
