This document discusses microplastic pollution and its potential threat to marine invertebrates and the food web. It defines microplastics and explains how they enter the marine environment. Studies found microplastics present in sediment samples from beaches around the world. Microplastics can be ingested by small organisms and transferred up the food chain, as demonstrated by studies showing zooplankton ingesting microplastics that were then found in mysid shrimp that ate the zooplankton. The document also discusses how microplastics can be taken up by blue mussels and transferred to shore crabs that eat the mussels, entering the intertidal food web.