Scanning electron microscope studies of the egg shell in some anostraca (Crustacea: Branchiopoda)

The tertiary shell of the eggs of anostracan crustaceans consists of two layers, an outer cortex and an inner alveolar layer. Scanning electron microscope studies show that, in most species, these layers are separated by a subcortical space which intercommunicates with spaces in the cortex and with the meshwork of the alveolar layer. No evidence was found for direct communication between pores on the surface of Branchipus stagnalis eggs and the subcortical space. No surface pores were found in the eggs of Branchinecta packardi, Chirocephalus diaphanus, Artemia salina, nor in eggs of the notostracan Triops cancriformis. Similarities in structure and possible functions of the egg shells of anostracan crustaceans and certain insects are discussed in relation to similarities in certain features of their environments.