(full paper is archived in the Miller Library)
Title: An analysis of the endogenous rhythms in jumping activity in an intertidal collembolid population on the central California coast
Student Author(s): McSpadden, Michelle Marie
Faculty Advisor(s): Burnett, Robin
Location: Final Papers Biology 175H
Date: June 1978
Keywords: biological rhythms in marine and maritime organisms
Abstract: Investigations of the rhythmic jumping activity of the intertidal collembolid Archisotoma besselsi has resulted in the following findings: (1) A circadian rhythmicity is present which indicates a sensitivity to the light-dark cycle of the solar day. (2) The free-running period for this rhythm is approximately 23.8 hours. (3) Different light regimes cause the rhythmic pattern to phase advance and delay in different ways, showing that the systems compensiate independently according to the particular imposed light cycles. (4) The circadian clock is entrained to a light-dark cycle at a point in the cycle approximately 2 hours and 30 minutes before dawn. (5) Phase shifts in persistent rhythms seemed to vary as a function of temperature. (6) The circadian activity peaks and a set of smaller peaks maintain a constant difference between their two periods, indication that the two rhythms are caused by separate endogenous oscillators. (7) A tidal clock may be the driving oscillator for this smaller activity peak.