Fig. 4. (A) Flexion and extension of the thoracic and abdominal segments during digging. Measurements were based on 6–8 selected video frames per animal (N=8). The drawings show extension and flexion of body segments. (B) The maximum angles of body segments during roll-up. The position of the animal during rolling up is shown in the drawing. Measurements were made as in A. Each column in A and B represents the mean value ± S.E.M. AS, abdominal segment; TS, thoracic segment. Numerals indicate numbers of body segments.