One oyster can filter a bathtub’s worth of water per day.

When they aren’t being served as delicacies, oysters are serving an extremely important ecological function: filtering prodigious amounts of water. An adult oyster can filter plankton, algae, and various debris from up to 50 gallons of water (the equivalent of a full bathtub) per day, feeding themselves and making their marine ecosystem a cleaner, healthier place for all manner of sea life in the process. 

Cleaner water allows sunlight to penetrate deeper into the brackish, coastal environments oysters call home and reach aquatic vegetation that thrives in submerged areas; this, in turn, provides more food for fish, turtles, and even sharks. Oysters’ filtration power is magnified when they cluster together and form reefs, which provide shelter and breeding grounds for even more sea creatures.