Embryonic development of the European smelt Osmerus eperlanus eperlanus (L.) (Neva population)

The embryonic development of the European smelt Osmerus eperlanus eperlanus has been described. The whole period of the development has been subdivided into 6 subperiods. More than 80 stages may be described for all of these periods. The development of the European smelt embryo was studied in the 5 different regimes of a constant temperature in the range 9.5–18.3°C. The duration of different stages under different temperature regimes was expressed in the relative units of τ 0 (the time of a single cleavage) and τ s (the time of formation of a single pair of somites). It was established that the τ s value had proportionally changed by embryogenesis. Due to this fact, the duration of the stages was expressed only as τ s . The dependency of the speed of the European smelt embryogenesis on temperature has been shown. This dependence was expressed using the standard interval τ s and described using the equation log τ s ( t ) = 3.22665−0.13876 t + 0.00297 t 2 , where t is the temperature.