Factors controlling emergence of pink shrimp (penaeus duorarum) from the substrate

TLDR: The persistence of the pattern of nocturnal activity for several days under conditions of constant low light intensity confirmed that emergence and subsequent activity were under rhythmic control.

Abstract: 1. A close relationship exists between the day-night cycle and the times of activity of pink shrimp. The shrimp bury beneath the substrate during the day but emerge at the time of sunset and are active at night.2. Emergence from the substrate is markedly synchronized in all members of the population. This study elucidates the mechanisms whereby this synchrony is maintained.3. The persistence of the pattern of nocturnal activity for several days under conditions of constant low light intensity confirmed that emergence and subsequent activity were under rhythmic control.4. Resynchronization of the phase of the rhythm controlling emergence to a shift in the light-dark cycle indicated that the light-dark cycle itself, or some component of it, is responsible for maintaining the relationship between emergence and the day-night regime.5. The close association between emergence and the time of light-dark transition indicated the possibility that the latter was the important component of the Zeitgeber responsible ...