Circadian rhythm in the locomotor activity of a surface-dwelling millipedeSyngalobolus sp.

Locomotor activity of the surface-dwelling millipede Syngalobolus sp. was r ecorded under laboratory conditions. Infra-red diodes were used to detect t he locomotor activity in an oval shaped chamber, which was connected with a n event recorder. The results of 11 individuals showed that the millipedes entrained to light/dark (LD12:12 h) conditions with negative phase angle di fference (-83.2 +/- 24.72 min). The millipedes showed a clear-cut free-runn ing rhythm with a period (tau) of 23.8 +/- 1.0 h (n = 9) in constant darkne ss (DD). The period in continuous light (LL) was relatively greater (25.2 /- 0.1 h; n = 3) than that in DD.