Scallops normally recess in the seabed sediments with their flat valve facing upwards, flush with the sea bottom and covered by sediment.
They are generally found in areas with strong currents, on a variety of seabed types, ranging from fine to coarse gravel, which may or may not be mixed with mud and organic matter. They feed on phytoplankton, bacteria, other micro-organisms and dead organic matter (detritus). Their most important sources of food are phytoplankton and microscopic algae found on the seabed substrate. The water currents supplies the food particles, and in many places factors such as the depth, tides and topography will affect variations in their access to food. Seasonal fluctuations in phytoplankton production also cause great variation in both the quantity and quality of nutrition available to the scallops. The distribution of great scallops in Norwegian waters is significantly limited by low winter temperatures and salinity. Climate change accompanied by milder winters may therefore result in an extension of their distribution northwards. Scallops have low tolerance of reduced salinity, and any change in the amount of fresh water entering coastal waters may also affect their distribution along the coast.