Preliminary investigations of the daily and seasonal locomotor activity rhythms of the spiny lobster,Panulirus argus

1. Group activity rhythms of Panulirus argus in the laboratory, as measured by constant recording actographs, are described under natural photoperiod and constant temperature for a seven‐month period. Adjunct behavioral observations are reported.

2. The data indicate seasonally varying daily rhythms are present in Panulirus argus. Starting times and duration of activity periods follow a seasonal trend ‐ the animals becoming active earlier, and maintaining their activity longer, during the spring and early summer months.

3. It is suggested that the evening's high level of activity is associated with increased social interaction and that photoperiod is an important factor in the daily and seasonal components Of the rhythm.