Circadian activity rhythms in colonies of ‘blind’ Molerats, Cryptomys damarensis (Bathyergidae)

Abstract

Various activity rhythms (general, feeding, and toilet) were measured under controlled laboratory conditions in two colonies of the Damara molerai Cryptomys damarensis, for 140 consecutive days (following a 30 day test period) under various photoperiod regimes (16:8 LD, 12:12 LD, and constant dark DD). As a general rule, all activities showed a significant diurnal rhythm with a period of 24 h under LD photoperiods. However, under a 16 : 8 LD photoperiod a very prominent activity component during the first part of the subjective night was observed, especially following a shift in photoperiod. The molerats responded rapidly to LD phase shifts. In constant dark, all activities had free-running periods of τ = 24,1-24,2 h, thus indicating that light can synchronize and entrain endogenous circadian rhythms in these molerats.