Generation time, length of life, instar duration and frequency of moulting, and their relationship to temperature in eight species of cladocera from the River Thames, reading.

Data on generation time, length of life, instar duration and frequency of moulting at a range of constant temperatures are given for eight species of epiphytic Cladocera from the River Thames. For each species each of the above events was inversely related to temperature. The number of juvenile instars was constant for a particular species, but varied between species; large species tending to have more juvenile instars than small species. A similar size relationship was found for generation time. Juveniles moulted more frequently than adults. The duration of an adult instar was the same as the duration of egg development, except at low temperatures. The data are compared with published data on daphniids, and possible reasons for the basic differences discussed.Regression analysis of the relationships between the various dependent variables and temperature required a logarithmic transformation. A reciprocal transformation was statistically inadequate for describing the relationship.