title: Dominance hierarchy-dependent behavioural plasticity of crayfish avoidance reactions.
abstract: Crayfish showed avoidance reactions when mechanical stimulation was applied to their tailfan. The response pattern of the avoidance reaction was dependent on crayfish size. Small crayfish showed an escape-like dart response while larger crayfish displayed a defensive-like turn response. We show that the response pattern to the same sensory stimulus changed with social status in the small crayfish. Crayfish are territorial animals and a dominant-subordinate relationship was determined when two previously unacquainted animals were paired. This winner-loser hierarchy was observed in pairs of small crayfish. Before fighting, all crayfish showed a dart response following mechanical stimulation of the tailfan. However, the probability of occurrence of a turn response increased significantly in the crayfish that won a fight. This behavioural transition from dart to turn response occurred immediately and was maintained for at least 3 days even if a dominant crayfish was isolated again with no opponent.
authors.affiliation: Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Sawako
authors.initials: S
authors.lastname: Fujimoto
authors.forename: Bunpei
authors.initials: B
authors.lastname: Hirata
authors.forename: Toshiki
authors.initials: T
authors.lastname: Nagayama
mesh_terms: D000374:Aggression / Q000502:physiology; D000818:Animals; D003400:Astacoidea / Q000502:physiology*; D001362:Avoidance Learning / Q000502:physiology*; D001522:Behavior, Animal / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology; D008297:Male; D008568:Memory / Q000502:physiology; D012919:Social Behavior; D012930:Social Dominance