COMPARISON OF THE GRADIENT OF SETAL DEVELOPMENT OF UROPODS AND OF SCAPHOGNATHITES IN ASTACUS LEPTODACTYLUS

¹ Laboratoire Biologie et Physiologie des Organismes Marins, Université P. & M. Curie, 4 Place Jussieu, 75230-PARIS 05, France

1. Characterization of the different stages of the molt cycle of Astacus leptodactylus has been established using morphological criteria of the setae observed through the uropod. This method is paraticularly useful for the scientist who wants to get replicable, physiological data without disturbing the animals.

2. Stages determined from uropod studies agree with those obtained from comparative studies of scaphognathites.

3. According to the seasons, a more or less quiet intermolt phase is observed. The animals either directly enter the premolt phase or are blocked in stage C4 or early DO. Therefore, the morphological stage DO seems to be heterogenous, and apolysis is not necessary to the onset of premolt.

4. A single mode of setal formation seems evidenced. Moreover, setae with compound or connected matrices are seen in the scaphognathite.

5. Number and mobility of blood cells in the uropods are related to the investigated stage. During the premolt stages hemocytes, especially granulocytes, are observed within the exuvial space.