Ultradian and circadian rhythmicity of behavioral activities in the young snail Helix aspersa maxima (Gastropoda, Helicidae)

Abstract

The rhythm of behavioral activities was studied in 8- to 100-day-old young snails (Helix aspersa maxima) and compared with that of adults. The animals were individually tested. Locomotor activity made up the main part of the total activity. The temporal distribution of feeding closely matches that of locomotion (involving displacement), while movements without displacement (i.e., movements of the head or shell) appeared sporadically. The activity of both the young and adults could be entrained to a 24-h light–dark cycle. Under constant conditions (dim red light) both the young and adults displayed free-running circadian rhythms, which were less robust in the young. Young snails also displayed short-duration rhythms with periods between 3 h and 5 h 30 min. This ultradian component is weak when the animals are subjected to a 24-h light–dark cycle, whereas it persists beyond 3 months in animals raised under constant conditions.