Eating, for an oyster, is pretty simple: Take water in, keep the tasty plankton, and spit water out. Increasingly, however, these mollusks are exposed to tiny pieces of plastic the same size as oysters’ preferred plankton meals. More plastic from various products and industrial processes ends up in the oceans each year, and over time, this waste breaks down into smaller and smaller pieces. In a study published online today in the Proceedings of the National Academy of Sciences, researchers show that when Pacific oysters (shown) are exposed to so-called microplastics in the lab, they ingest a large proportion: 69% of the 6-micrometer particles added to the water. These end up in the oysters’ guts and make the animals invest less energy in reproduction, either by disrupting their digestion or their hormone systems. Female oysters exposed to microplastics made 38% fewer eggs, and males made sperm that were 23% slower. Plus, they had fewer offspring, which were themselves slower to reach maturity. This could create difficulties for aquaculture—Pacific oysters are grown for food around the world, and other filter feeder favorites such as mussels and sea cucumbers may be similarly affected.