European Flat Oyster

Ostrea edulis

Ostrea edulis, known as the European flat oyster, features a unique oval or pear-shaped shell that typically ranges from 3.8 to 11 centimeters in width. The shell can appear in shades of white, yellowish, or cream, with a rough outer texture that often displays pale brown or bluish concentric bands on the right valve. The left valve is concave and adheres to the substrate, while the right valve is nearly flat. This species inhabits the western and southern coasts of Europe, extending from Norway to Morocco and throughout the Mediterranean. It is commonly found in estuarine and shallow coastal waters, attaching itself to hard substrates like mud and rocks, generally at depths of up to 80 meters, though most sightings occur shallower than 40 meters. As a filter feeder, Ostrea edulis primarily consumes phytoplankton suspended in the water. Most individuals begin life as males, reaching sexual maturity within eight to ten months, and can change sex depending on environmental conditions. Each year, they can produce between 500,000 to over a million eggs, with larvae developing in the mantle cavity before being released into the surrounding water. Divers may encounter this species nestled among rocks or mud, often forming aggregations in their preferred habitats. Ostrea edulis has been a food source for humans since ancient times, but its populations have faced significant declines due to overfishing, pollution, and disease. Restoration efforts are currently being implemented in various European countries to rebuild oyster reefs and protect their habitats.