Subdivisions of stage E (ecdysis) in the crayfish Orconectes virilis

Abstract

Recent studies on the environmental regulation of molting in the crayfish Orconectes virilis have indicated that the death of an animal during exuviation may be important to the understanding of the physiology and endocrinology of ecdysis. In O. virilis molt mortalities may occur at any of four distinct points during stage E, and the practice of describing a molt mortality as occurring "when well along in the molt" is inadequate. To introduce more precision into the reporting of such mortalities the following classification is proposed.Stage E₁: the thoracoabdominal intertergal membrane is distended and the posterior margin of the carapace is elevated slightly. Stage E₂: the carapace is thrown forward and the cephalic structures are withdrawn. Stage E₃: the abdomen and related components are withdrawn. Stage E₄: the chelipeds and other walking legs are withdrawn.