Effects of permanent and variable illumination on development of the clawed frog Xenopus Laevis larvae

The clawed frog Xenopus laevis larvae were grown (from the begining of the active feeding of larva transformation into young of the current year) in aquariums under different constant and variable illumination. The growth and rate of developing tadpoles in aquariums under the absence of permanent light (0 lx) significantly decreased, and the variability and mortality of them increased. A similar pattern was obseved in the young of the current year: the mortality of them was higher by 2.3 times. Possible mechanisms of light and dark effects on the growth and development of the clawed frog larvae,are discussed. Under the variable illumination (6004200 lx) the growth, development activated, the mortality and variability of tadpoles (and young of the current year) decreased to a greater degree as compared to the control illumination (2400 lx). The results obtained attest that the variation of the illumination within definite ranges is more favorable that any constant conditions.