Oysters are one of the most well-known types of shellfish. Like their cousins, the mussels, oysters have two shells seemingly sealed together. Their strong muscles shield the delicate meat perfectly from the outside world. They prefer to inhabit shallow coastal areas, where they live together in large groups called oyster beds. Nowadays these colonies are mostly man-made and exist rarely as a natural phenomenon.
Oysters are hermaphrodites and, although they grow as males, become female for isolated phases in order to reproduce. This depends on the temperature and conditions in their habitat. Only with increasing age do oysters get their shell valves. These valves have an irregular and rough surface. Optimally oysters can live for up to 30 years.
Oysters must be at least three years old to be consumed. During this growth period in breeding farms the oysters are regularly cleaned by smaller mussels, this ensures their high quality. Oysters feed on fine plankton particles.