A circadian locomotor rhythm in the giant land snail, Achatina fulica.

A circadian rhythm in the locomotor behavior of the giant land snail, Achatina fulica, was studied by a running wheel method in a 24 hr light-dark cycle (LD 12:12) and also in constant dim light. The locomotor rhythm could be entrained to the LD cycle, and the entrained rhythm was characterized by the bulk of activity in the dark period, the major activity appeared in the first half of the dark period. In constant dim light the locomotor rhythm free-ran with a period of about 24 hr.