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Lifecycle of the pearl mussel

Pearl Mussel by Sue ScottPearl Mussel by Sue Scott

The lifecycle of the freshwater pearl mussel is very complex and also very unusual. The male pearl mussels release sperm into the water, which is then filtered by the females. The eggs are fertilised, and develop in the female’s breeding pouch before being released as larvae. Each female mussel can release up to 4 million larval mussels. These larvae (also known as glochidia) are then washed downstream by the flow of the river, and if they are lucky they attach themselves to the gills of young salmon or trout. The young mussels live as a parasite on the gills of the fish for approximately nine months, before dropping off the fish and settling into the river gravels. They then grow in the river bed and develop into juvenile pearl mussels. The juvenile mussels take about 15 years to mature, and during this time they are very sensitive to pollution and sedimentation.

Lifecycle of the Pearl Mussel