Duration of socialization influences responses to a mirror: responses of dominant and subordinate crayfish diverge with time of pairing

SUMMARY Reflective surfaces have been shown previously to modify behaviour in socialized crayfish. Socializing crayfish by pairing them for two weeks established a hierarchy with one dominant and one subordinate crayfish per pair. Dominant crayfish exhibited specific behaviours, such as cornering,turning and crossing, more frequently in a reflective environment than in a non-reflective environment. After 2 weeks of pairing, subordinate crayfish did not respond in this manner but, instead, performed more reverse walking in a reflective environment. The present study investigated how the length of social pairing affects the response to mirrors. Crayfish from a communal tank were paired for 30 min or for 3 days, and their activity was videotaped for 20 min in a test aquarium lined with mirrors on one half and a non-reflective matte lining on the other half. Crayfish housed in the communal tank were used as a comparison group. After 30 min of pairing, dominant and subordinate crayfish responded similarly to the reflection, showing essentially the same pattern for seven of nine behaviours examined. After 3 days of pairing,dominant crayfish continued to respond to the reflection in essentially the same way, but subordinate crayfish behaved differently, showing differences in seven out of nine behaviours. Thus, the pattern of responses of dominant and subordinate crayfish to reflection diverged with time of pairing.