Proecdysis, setal development, and molt prediction in the American lobster (Homarus americanus). J. Fish. Res. Board Can. 30: 1337-1344.Setal development and proecdysial cuticular changes can be observed in the pleopods of the American lobster (Homarus americanus) from earliest Do through stage D3, and with pleopod staging criteria it is possible to follow proecdysis from beginning to end. A technique is described for recognition of a1l stages and substages of proecdysis, for evaluating effects of various treatments on proecdysis, and for predicting time of ecdysis where holding temperature is known. Histological comparisons between the pleopods and the general integument suggest a universal criterion for stage D2, and a need for adjustment in some accepted molt stage criteria. Development plateaus occur in stage D6 instead of Ca in this species, and this suggests that the concept of stage C anecdysis may be incorrect. Arrnx, D. E. 1,973. Proecdysis, setal development, and molt prediction in the American lobster (Homaras americanus). J. Fish. Res. Board Can. 30: 1337-1344.On peut observer le d6veloppement des setae et les changements cuticulaires de la proecdysie sur les pldopodes d'Homarus d partir du tout d6but de Ds jusqu'au stade D3 et, par des critdres d6finissant les stades des pl6opodes, il est possible de suivre la proecdysie du d6but d la fin. L'auteur ddcrit une technique permettant d'identifier tous les stades et sous-stades de la proecdysie, d'6valuer les effets de divers traitements sur la proecdysie et de prddire 1'6poque de I'ecdysie lorsque la temp6rature d laquelle les homards sont maintenus est connue. IJne comparaison histologique entre les pl6opodes et Ie t6gument g6n6ra1 suggdre un critdre universel pour le stade D2 et un besoin de reviser certains critEres accept6s des stades de la mue. Il se produit des plateaux dans le d6veloppement au stade Ds plut6t qu'au stade Ca chez cette espdce, ce qui donne d croire que le concept d'anecdysie au stade C est peut-Otre erron6.
Osmoregulation and salinity tolerance were studied in larvae and post-larvae of two species of crustaceans. Homarus americanus and Penaeus japonicus, that have different types of embryonic development.In both species, salinity tolerance decreased through the larval stages, was at a minimum at metamorphosis, and increased in post-larval stages. In H. americanus, the lethal salinity for 50% of the animals (24 h LS50) at 20C was about 1 7%o at metamorphosis, and about 10.5-12%o in stages IV and V. In P. japonicus, the 24 h LS50 at 25C was about 25%o at metamorphosis, and about 7-10% from the sixth post-larval stage onwards.In both species, larvae were hyper-osmoconformers and the osmoregulatory pattern changed after metamorphosis to the juvenile/adult type. In //. americanus, stages IV and V slightly hyper-osmoregulated in low salinities. In P. japonicus, post-larvae hyper-hypo-regulated, and their regulatory capacity increased up to the fifth post-larval stage.In young stages of H. americanus and P. japonicus, Osmoregulation and salinity tolerance appear correlated, and are modified at metamorphosis. These results are discussed iih regard to their ecological and physiological implic i md to previous studies on other species.
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