Characterization of the moult cycle in Neocaridina denticulata sinensis Kemp, 1918: the moulting frequency, moulting stages, and haemolymph ecdysteroid levels

Abstract

Abstract This study aims to elucidate the physical evidence of the moulting stages and the characteristics of ecdysteroid levels in the moulting cycle of Neocaridina denticulata sinensis. From hatching to the first complete pleopod development, N. denticulata sinensis moults 14 times at 25°C in the laboratory. The whole process was divided into four stages based on the moulting characteristics during the various intervals. Using the structural changes of the telson and Drach’s classification system, four moulting periods (postmoult, intermoult, premoult, and ecdysis) were recognized. In addition, based on the changes of the setal lumen, internal cone, and the epidermis, the premoult period was further divided into five substages (D0, D1, D2, D3, and D4). Despite similar fluctuation patterns in mature males and females, significant differences of haemolymph ecdysteroid titers were revealed in postmoult, intermoult, and premoult. These works will provide an important additional reference for the exploration of the moulting mechanism in crustaceans.