More than 10 million tons of plastic debris enter the oceans every year and are found in nearly every oceanic layer. They start out as large floating items and eventually break down into much smaller pieces called microplastics. These particles are pervasive and have been found in the digestive tracts of more than 100 different species, posing physical, chemical and even potential biological harm to these animals. Mussels and other bivalves like oysters and clams are eaten whole without removal of the gastrointestinal tract and therefore represent a pathway for microplastics to enter the human food chain.