Culture of fish food organisms

Unit 3 - Cladocerans

3.2.2.2.Life Cycles of Moina

The reproductive cycle of Moina has both a sexual and asexual phase. Normally, the population consists of all females that are reproducing asexually. Under optimum conditions, Moina reproduce at only 4-7 days of age, with a brood size of 4-22 per female. Broods are produced every 1.5-2.0 days, with most females producing 2-6 broods during their lifetime. Under adverse environmental conditions, males are produced and sexual reproduction occurs resulting in resting eggs (ephippia). The stimuli for the switch from asexual to sexual reproduction in populations of Moina is an abrupt reduction in the food supply, resulting in an increase in resting egg production. However, it is advantageous to keep the population well fed and in the asexual mode of reproduction, since fewer progeny are produced with resting eggs.