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Biol Bull 63: 442-455. (December 1932)
© 1932 Marine Biological Laboratory
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A COMPARISON OF THE LIFE HISTORIES OF MICTIC AND AMICTIC FEMALES IN THE ROTIFER, HYDATINA SENTA

JOSEPHINE CAROLYN FERRIS 1

1 DEPARTMENT OF ZOÖLOGY, UNIVERSITY OF NEBRASKA

This paper deals with a comparison of the life cycle of the bisexual rotifer, Hydatina senta. The three types of individuals, amictic, unfertilized mictic, and fertilized mictic females are compared as to the periods of their life histories.

The mean length of life for the amictic females is 192.95 ± 2.1947 hours; for the unfertilized mictic females 170.43 ± 1.3051 hours; and for the fertilized mictic females 172.43 ± .4983 hours. More than half of the amictic females survive the modal life duration.

The longer life of the amictic females, as compared with the mictic, results from the probable differences in metabolic rate of the two. The amictic and mictic females produce practically the same number of offspring, the mean fecundity for the amictic is 45.39 ± .3261 and for the unfertilized mictic 42.520 ± .5288.

The mean duration of the fecundity period of the amictic female is 81.25 ± 1.1250 hours with a standard deviation of 22.53 ± .7819 hours and a coefficient of variability of 27.72 per cent. The mean for the unfertilized mictic female is 54.35 ± 1.1061 hours, the standard deviation 17 ± .7851 hours, the coefficient of variability 31.20 per cent.

In summary, the amictic and mictic females produce practically the same number of eggs but those of the mictic female are laid in a shorter time and the amictic female usually lives a longer life. The relative longevity of the amictic and mictic female of Hydatina senta is not correlated with the relative fecundity. (See Tables VII and VIII.)

[See table in the PDF file]

The mictic females of this species may be fertilized during immaturity. The fecundity of the mictic female is reduced by fertilization; the mean number of eggs being 9.97 ± .3015, standard deviation 4.20 ± .224, and the coefficient of variability 42.18 ± 2.1388. The length of life of the mictic female is not appreciably altered by the production of fertilized eggs. The mean length of life for the fertilized mictic is 172.43 ± .4983 hours and for the unfertilized mictic females 170.53 ± 1.3051 hours.






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Copyright © 1932 by the Marine Biological Laboratory.