Health effects of microplastics have been determined for many species because there is concern both about their health and about the effects of microplastic on individual organisms and on ecosystems. The effects of microplastics on the health of a variety of single-cell and multi-cellular organisms [, sponges, water fleas, and daphnids, nematodes, sea urchins, oysters, clams, invertebrates (crabs, the crustacean Hyatella azteca, snails, lugworms, and fish zebrafish(Danio rerio)) , European perch, Japanese medaka (Oryzias latipes), goby (Pomaschistus microps), and European sea bass (Dicentrarchus labrax)] have been studied. Many effects were noted, including reduced feeding and photosynthesis, intestinal damage and inflammation, changes in oxidative stress and stress-related genes, reduced reproduction, changes in intestinal bacteria (the intestinal microbiome), and inhibition of acetylcholinesterase (AChE).