Cyclomorphosis: The Adaptive Mechanism of Zooplankton in the Aquatic Ecosystem

^1,2Department of Animal and Environmental Biology, Faculty of Life Sciences, University of Benin, Benin City, Nigeria.

^*Corresponding Author

Joyce Osarogie ODIGIE

Department of Animal and Environmental Biology,

Faculty of Life Sciences,

University of Benin, P.M.B. 1154,

Benin City,

Nigeria.

Email: joyce.odigie@lifesci.uniben.edu

Mobile: +2347036960280

Abstract

Cyclomorphosis is a temporal, cyclic or induced morphological change that occurs in the planktonic population, primarily as the outcome of abiotic or biotic factors in the environment. This phenomenon is noted in the dinoflagellates, rotifers, cladocerans and much strikingly in the copepods. In this study, search engines like the Google Scholar, National Science Library, PubMed and journal sites like the journal of freshwater biology were used for the literature search. Search terms include aquatic ecosystem, cyclomorphosis, rotifers, cladocerans, zooplankton, copepods and dinoflagellates. Detailed evidence-based literature was used to review the adaptive mechanisms of cyclomorphosis in an aquatic ecosystem. The research results suggest that the change that occurs in the lorica, size and number of outer ornamentation like spines and the shape of mastax in accordance to body shape is remarkable in zooplankton. The degree to cyclomorphosis which is developed within different populations of the same species is variable. Organisms can produce cyclomorphic variability in the tropical and subtropical regions as there is sufficient temperature difference among the seasons. The total body size may increase, decrease or remain the same throughout the cycle, depending on the species. Organisms produce exuberances that are not retained in all generations. However, little attention has been previously given to the non-exuberant side of cyclomorphosis. This review concludes that studies in cyclomorphosis are gradually going into extinction, as most of the works done were carried out in the past. Hence, the need for a revival of cyclomorphic research interest in this part of the world.

Keywords:Cladocerans, Copepods, Cyclomorphosis, Rotifers, Zooplankton

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