Eelgrass is one of the few marsh plants to grow under water in coastal wetlands. Eelgrass beds are home to a variety of animals, including perfectly camouflaged pipefish that look like leaves with eyeballs. Other wetland inhabitants, like worms and shrimp, burrow in the mud around its roots. The blades provide mooring for herring eggs, hydroids and others.
In the 1930s, eelgrass almost completely disappeared from both sides of the Atlantic due to unusually high water temperatures.
Seeds were harvested and used like wheat by the Seri Indians in the Gulf of California.
Eelgrass is one of the few flowering plants that grow in the oceans.