Learning and remembering the environment in the blind cave fishAnoptichthys jordani

Summary

• 1. The swimming behavior of blind cave fish (Anoptichthys jordani) differs in familiar and unfamiliar surroundings. Following release in unfamiliar surroundings, or after alterations of a familiar environment, the fish increase swimming velocity in order to optimize lateral line organ stimulation. Furthermore, they glide along boundary features more often than they do in familiar surroundings. These characteristics of swimming behavior were used to measure the occurrence and duration of exploratory behavior.

• 2. Fish removed from a familiar environment for as long as 2 days spend less time exploring when returned than when they were initially placed in the environment. After a longer absence no difference was found between the duration of the initial and subsequent exploration.

• 3. When blind cave fish were anesthetized by cooling after 4 h of exploration in a novel environment, they explored the environment anew following recovery from anesthesia. However, when anesthetized after 6 or 30 h of exposure to the environment, renewed exploration was not observed.

• 4. The shape of the tank was found to determine the duration of the fish's exploration. Bilaterally symmetrical tanks were explored longer than tanks with no axis of symmetry, even if the axis of symmetry is destroyed by relatively small objects, such as bars attached to the walls of the tank.

• 5. The data presented support the hypothesis that during exploration, blind cave fish develop an internal (cognitive) map of their environment that contributes to subsequent spatial orientation.