Study of polymorphism of two Rotiferan species in Mzareeb Lake

Rotifers considered as one of the important zooplankton in the ecological system of fresh water lakes. It’s an essential food for many species of fish. So, it’s important to be available all over the year with enough abundance. In the predator presence, polymorphism is considered an effective way for the species protection. For that reason, one spine or more of the studied species (Keratella cochlearis, Brachionus calyciflorus) are being built at the same time where the predator (Asplanchna priodonata or different species of crustaceans) are in the lake. These spines usually disappear during the predator absence. This study also reveals that there is no clear role for the temperature or abiotic factors in the polymorphism operation.