Behavioural analysis of coordinated feeding movements in the gastropodLymnaea stagnalis (L.)

Summary

Radula movements, side-to-side movements of the head and locomotion of the whole animal were investigated in feedingL. stagnalis.

• 1. The radula was observed to move rhythmically every few seconds (Figs. 2 and 4).

• 2. The interval between successive radula movements was unaffected by whether the direction of head movement had changed or not (Fig. 3).

• 3. Changes in the direction of head movement (head reversals) occurred between radula scrapes, not during them (Fig. 2).

• 4. A head reversal did not occur after every radula movement so that many radula movements could occur between two head reversals (Fig. 5).

• 5. Altering the temperature by 10.5 °C affected both the inter-radula interval and the inter-head reversal intervals in such a way that head reversals continued to occur between radula movements (Fig. 8).

• 6. Altering the temperature by this amount did not affect the number of radula movements occurring between two successive head reversals, i.e. it did not affect the probability that a given radula scrape would be followed by a head reversal (Fig. 9).

• 7. The number of radula movements occurring between two head reversals was negatively correlated with speed of locomotion (Fig. 10).

• 8. The sideways distance between two radula scrapes was variable, but was not found to be related to forward speed (Table 1).