Every animal shows struggle for an existence in their natural habitat for their successful life. Every animal has its own natural behaviors, even a slight change in the environment may change its own physical behavior like movement, immersed in the water, hiding inside the shell for protection, feeding habit, response to touch and physiological behavior viz., mucous secretion, Excretion, Parturition etc. In the present study the abundantly recorded snails, Thiara lineata is filter feeder and occupies first step in the food chain. In present investigation,behavior in the natural habitat and in laboratory conditions by exposing to safe concentration of predetermined LC 50 of pesticides like Endosulphan, Nuvacran, Cymbush and Sevin.