Journal Article

AGE GROUP DETERMINATION BY ANALYSIS OF THE CUTTLEBONE OF THE CUTTLEFISH SEPIA OFFICINALIS L. IN REPRODUCTION IN THE BAY OF BISCAY

R. le GOFF, E. GAUVRIT, G. PINCZON DU SEL and J. DAGUZAN

in Journal of Molluscan Studies

Published on behalf of The Malacological Society of London

Volume 64, issue 2, pages 183-193
Published in print May 1998 | ISSN: 0260-1230
Published online May 1998 | e-ISSN: 1464-3766 | DOI: https://dx.doi.org/10.1093/mollus/64.2.183
AGE GROUP DETERMINATION BY ANALYSIS OF THE CUTTLEBONE OF THE CUTTLEFISH SEPIA OFFICINALIS L. IN REPRODUCTION IN THE BAY OF BISCAY

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Very few hard pieces of evidence can be used to determine the age of the cuttlefish Sepia officinalis. We have studied the cuttlebone of cuttlefish living in Southern Brittany over a complete life cycle (from 1988 to 1990) in order to separate clearly the two age groups existing in this area. Cuttlebone is formed with successive calcium carbonate lamellae formation during growth. The rhythm of lamellae deposition is not constant and appears to be closely linked with temperature. It reaches a maximum in summer (18.75 lamellae per month) and falls drastically in winter (1.6 lamellae per month). The lamellar thickness measured on the mid-sagittal surface of the hypostracum shows characteristic zones of narrow lamellae. The first series of narrow lamellae appears at the 9th lamella and is formed just after hatching. The second one, seen only in group II breeders, is located between the 45th and 60th lamellae. This takes place in May when this group begins its first spring migration to the coast. This second set of narrow lamellae is also visible on the siphuncular surface of the phragmocone by an inflexion point. A final series of narrow lamellae is formed during the season of reproduction and appears in both groups of breeders. During the breeding season, the separation of the two year-classes of breeders is also possible by counting the total number of lamellae formed. Group I has a minimum of 80 lamellae whereas group II has about 120.

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Subjects: Aquatic Biology ; Evolutionary Biology ; Zoology and Animal Sciences

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