© 1987 by ICES/CIEM International Council for the Exploration of the Sea/Conseil International pour l'Exploration de la Mer
A living tag for recording moult histories in crustaceans
Department of Zoology, Adrian Building, School of Biological Sciences, University of Leicester University Road, Leicester LEI 7RH, England
DAFS Marine Laboratory P.O. Box 101, Victoria Road, Aberdeen AB98DB, Scotland
A method for tagging lobsters with epidermal implants is described. Rectangular or square pieces of cuticle and attached epidermis obtained from donor animals were inserted into the abdominal haemocoel of hosts. The donor material from recently moulted animals was obtained from the chela, dorsal cephalothorax, or dorsal abdomen. These cuticular "tags" were inserted into the second or third abdominal segments of the hosts through small slits in the exoskeleton. Some implants were inserted ventrally through the thin sternite cuticle, others dorsally through the arthrodial membrane.
Such implants form cysts in which the epidermis on the inner surface of the tag grows around the cuticular component to surround it completely. The epidermis continues to secrete cuticle in step with the host animal. At the apolysis following implantation, when the host begins to form its new cuticle, the epidermis of the tag separates from the original implant cuticle and begins to form a new cuticular layer. Since the epidermis completely surrounds the tag and cuticle is secreted towards the centre of the cyst, the successive layers of cuticle are not lost at moulting. By sectioning tags and counting the number of cuticular layers the moult history of the host can be as certained.
The possibility that the cuticular sleeve which surrounds abdominal "streamer" tags could be used as a moult recorder was also examined. However, in that case the cuticle is external to the animal and sloughed cuticular layers are lost soon after each moult.