A study of the development of a local fresh-water crab, Potamon edulis (Latreille)

Abstract

A preliminary study of the changes undergone by the egg of Potamon edulis, the Mediterranean fresh water crab, during its embryology was undertaken. Due to the great difficulties encountered in the embedding and sectioning of the macroelecithal eggs and hence unsuccessful sectioning of the early stages, the work was concentrated on changes in the external features of the egg and some histological studies of he post-naupliar development stages. This was done by examining whole preserved eggs under a dissecting microscope and whenever possible by partial dissection. Previous workers (Thompson 1836, Mercanti 1887, Lanchester 1901, Calman 1909, Annandale et al 1913, Koba 1936, Pc.Cann 1937, Bishop 1967) have reported the absence of free larval stages in the development of the Potamonids. This was confirmed in the present work and an attempt was made to find any stages which correspond to the free living larval forms found in other Decapod crustacea. The general developmental pattern was contrasted with that of crustacea in general and more specifically with the marine Decapoda and the differences were related to the special environment in which Potamon edulis lives and reproduces.