THE EXISTENCE OF A SHORT REPRODUCTIVE CYCLE IN ANODONTA IMBECILLIS

¹ U. S. BUREAU OF FISHERIES LABORATORY, FAIRPORT, IOWA

Anodonta imbecillis cannot be classed with either long or short term breeders as defined by Lefevre and Curtis. In specimens obtained at Fairport, Iowa, a complete reproductive cycle (including metamorphosis from glochidia to juvenile mussels, for reproduction in this species does not depend on parasitism) is completed in from 3 to 4 weeks during the late summer. Another cycle begins after an interval varying from 2 to 3 days to 2 weeks. Gravid A. imbecillis have been found in all months but April. It is possible therefore that this short reproductive cycle is repeated throughout the year.