Grooming in crickets: Timing and hierarchical organization

The variations in structural and timing principles underlying grooming are examined in the cricket Teleogryllus oceanicus. Two situations were studied: normal grooming and grooming that appears with locomotion in an unfamiliar environment. Normal grooming appears to be controlled by a hierarchy of random processes. Transitions between grooming acts are based on anatomical proximity, while hierarchical clusters are based on body regions. Acts per bout, acts per cluster, and clusters per bout are all random variables that follow geometric distributions; pauses between acts are also randomly distributed. In the unfamiliar environment, time-sharing appears to control the transition between locomotion and grooming. The study shows how a hierarchy can account for timing as well as structure in a behavioural sequence and how control principles change with variations in functional priority.