This study aims to determine toxic effects of polyester-based polymers (polycarbonate (PC), polyethylene terephthalate (PET) and, polybutylene terephthalate (PBT)) depending on physiological change in life cycle of Daphnia magna Straus (1820) (Cladocera, Crustacea). As a result of acute toxicity test, it was observed that although the rates of immobilized/dead organisms were low, damage started occurring in organisms. According to the results of 72^th, the median effective concentration (EC₅₀) values of PC, PET and PBT were determined as 2.604 mg L^-1, 4.694 mg L^-1 and >100 mg L^-1, respectively. In consequence of chronic toxicity test, in the experiment set in which the water where daphnids were cultivated was used, it was observed that there was a high rate of deformation on daphnids which were exposed to ester-based polymers. The possible effect of polyester-based polymers on the daphnids deformation might be consequence of reaction between urea and ester groups of PC, PET, and PBT. Especially in the sets where microalgae existed and the natural conditions were simulated, it was determined that the toxicity response of daphnids varied in accordance with different microplastic types in terms of their chemical structure.