Rudiments of an ability for time measurement in the cavernicolous fish Anoptichthys jordani hubbs and innes (Pisces Characidae).
Rudiments of an ability for endogenous time-measuring are indicated a) by bimodal activity in the dark phase of LD-cycles of 16:16 or 24:24 h and b) by damped activity oscillations frequently following a transition from LD to constant conditions. These oscillations always have the same period length as the applied LD.
D000818:Animals; D005075:Biological Evolution; D001766:Blindness; D002940:Circadian Rhythm; D005260:Female; D005399:Fishes / Q000502:physiology*; D008027:Light; D008124:Locomotion; D008297:Male