Conditions of Development and Hatching from Resting Eggs in Polyphemus pediculus (Crustacea: Branchiopodiodes)

摘要

The young of P. pediculus hatch from resting eggs only after their stay in water at 2-6℃ for not less than 4-5 months. Hatching takes place at temperatures of 2-8℃. Eggs retain their viability and produce the young after staying in water at 15-21℃ and 0℃ for 1.5-2 years and after drying for 9-12 months. Conditions of development and emerging of the young are genetically determined and are a consequence of combined effects of endogenous and exogenous factors, environmental temperature being the main factor. Duration of the dormancy period, rates of development of eggs and hatching of the young depend on the time when the eggs were laid, density and size of the laying, environmental conditions, and duration of their action at the dormancy and hatching periods.