VARYING FILTER STRUCTURES IN SELECTED CLADOCERAN SPECIES

The morphology of filtering apparatus of three cladoceran species viz. Daphina similis, Simocephalus vetulus and Moina macrocopa was investi gated by scanning electron microscopy. In the majority of these cladoc erans. the intersetular distances or the mesh size showed a normal dis tribution and the mean values ranged between 0.08 to 0.79 mu m. The to tal filtering area increased as a direct function of body length. In t he relationship between mesh size and filtering area, two types of all ometric growths were noted (i) with increasing body length the mesh si ze remains small, but there is a significant increase in the filtering area (S. vetulus), (ii) both mesh size and filtering area increase wi th body length (D. similis), the FA remains small but the mesh size be come larger (M. macrocopa).