Spatial learning in Japanese eels (Anguilla japonica)

Japanese eels (Anguilla japonica) were trained on a Morris-type spatial learning task. There were four tubes in a pool, but the eels could hide in only one of these. The eels learned the position of the open tube, and maintained their performance when the pool was rotated to remove possible intra-maze cues. The eels could not maintain their performance in a dark room, suggesting that spatial learning involved extra-maze visual cues. When the position of the open tube was randomly changed every day, the performance of the eels in finding the open tube did not improve.