Oysters are sessile invertebrates from the phylum Mollusca that form colonies called beds or reefs. They are bivalves, with exoskeletons in the form of a hard limestone shell and a fold of the body wall known as a mantle that produces the shell.

Oysters are filter feeders, meaning they use their gills to strain phytoplankton (one of their main food sources) out of the water. They also use their gills to absorb oxygen from the water. An adult oyster can filter up to 50 gallons of water per day, contributing to a healthy water system.

oyster parts