Tongue movements in the common boa (Constrictor constrictor)

Tongue movements were studied in Contsrictor constrictor by direct observation and by analysis of motion pictures. Vertical tongue movements consisted of an invariant sequence of protrusion, oscillation up and down, and retraction. Lateral deviation of the tongue occurred only in the company of vertical movements and was correlated with the direction of movement of the snake's head. Flick cluster duration varied from about 80 ms to about 1 s; variation in oscillation phase duration accounted for 69 per cent of the total variation. Oscillation phase duration varied linearly with the number of flicks in the flick cluster, suggesting that flick cluster duration is determined primarily by the number of oscilations which are carried out at a constant rate.