GROWTH AND CUTTLEBONE MICROSTRUCTURE OF JUVENILE CUTTLEFISH, SEPIA-OFFICINALIS L, UNDER CONTROLLED CONDITIONS

The periodicity of deposition of growth increments in the cuttlebone o f juvenile Sepia officinalis was investigated under controlled conditi ons for a short period after hatching (19 days). The slope of time ela psed and increment counts was significantly different from 1 indicatin g that lamellae are not deposited on a daily basis. The relationship b etween increment counts and juvenile length was, however, highly signi ficant. Also significant were the relationships between the number of growth increments and shell length and increment counts and cuttlebone area. These data show that the number of growth increments is related primarily to the growth rate of the juvenile rather than to its chron ological age. Taking into account these data, the cuttlebone lamellae cannot be used for age determination in the juvenile cuttlefish just a fter hatching.