Habituation Learning in Cuttlefish
by: Deann Dixon, Major: Psychology
Aleta Estrada, Major: Animal Behavior
Ryan Suarez, Major: Psychology
Habituation involves the waning of a response to a repeatedly presented stimulus that is not associated with events of biological significance. The evidence for habituation learning in cuttlefish (Sepia officinalis and Sepia pharaonis) is not convincing. Habituation like effects were reported by Sanders & Young, 1940; Messenger, 1973; and Messenger, 1977. For each of these studies, the experimental paradigm was the same. A cuttlefish was placed in a tank and presented with prawns that were contained within a glass tube. The cuttlefish would show is species typical attention, position, and attack responses. Strike response rates decreased within and between sessions and this response was interpreted as habituation. The cuttlefish may have stopped striking the glass because it hurt to do so, not because it habituated to the sight of the prawn. Evidence that striking the glass was painful was demonstrated by Messenger, 1973. Messenger clipped off the two tentacles and presented cuttlefish with prawns held in a tube. Without tentacles, cuttlefish persisted in “striking” the glass for a significantly longer period of time than cuttlefish with tentacles. Still, even with no tentacles, the strike response rate decreased within a session. It is possible that the decrease of the “pseudo-strike” demonstrated habituation. But, it is also possible, that the decrease in striking behavior was attributable to motor fatigue.
In light of the lack of evidence for habituation learning in cuttlefish we conducted a study to determine if cuttlefish are capable of habituation learning and to see if they exhibit both short-term and long-term habituation effects. Twenty-four cuttlefish were obtained from the National Resource Center for Cephalopods in Galveston, Texas and then placed in individual tanks. Cuttlefish were maintained in a closed water filtration system and were fed frozen shrimp. Cuttlefish were assigned randomly to one of four groups. Group Fish-Fish received a 25-minute exposure to a one-gallon glass container that contained a small fish. After 25 minutes the container was removed and replaced in the tank for five more minutes. Group Shrimp-Shrimp received a 25-minute exposure to a live shrimp. The container was removed and then replaced for five minutes. Group Fish-Shrimp were exposed to a fish for 25-minutes and then the container was replaced for five minutes with a container that held a live shrimp. Group Shrimp-Fish received a 25-minute exposure to a live shrimp followed by five minute exposure to a live fish. Trials were conducted daily for a total of ten days and all trials were videotaped. All groups showed both short-term habituation and long-term habituation effects. In addition, groups Fish-Shrimp and Shrimp-Fish shoed dishabituation effects, though the dishabituation effect for group Fish-Shrimp showed dishabituation effects, though the dishabituation effect for group Fish-Shrimp was stronger than that shown for Shrimp-Fish. No dishabituation effects were seen for groups Fish-Fish and group Shrimp-Shrimp. The finding that changing the stimulus from fish to shrimp or from shrimp to fish caused the cuttlefish to resume striking the container ruled out explanations based on motor fatigue or pain avoidance and supported our contention that cuttlefish are capable of habituation learning. This is the first time habituation effects have been observed in this species under controlled conditions.