This sea otter (Enhydra lutris) is resting comfortably in eelgrass (Zostera marina), which is a type of seagrass in the Elkhorn Slough (an estuary in Moss Landing, CA). Eelgrass is important for combating global warming by soaking up carbon dioxide from the water and atmosphere and by reducing the effects of erosion due to coastal storms. Researchers have been studying the effects of sea otters on their ecosystem and it turns out that sea otters are vital in maintaining the health of these eelgrass meadows by keeping the crab population in check. Crabs eat the sea slugs that eat the algae that grow on the eelgrass, which when the algae becomes too abundant prevents enough sunlight from reaching the eelgrass leaves. Sea otters eat crabs – one of their favorite foods – which then allows more sea slugs to thrive, such that the algae that grows on the eelgrass leaves is kept in check, thereby allowing the eelgrass to be greener and healthier. In fact, scientists have found that in environments where more sea otters are present, the eel grass is the most green and healthy!