The Sea Lamprey is an eel-like fish that can survive in both freshwater and saltwater, although an adult spends most of its life at sea. It is also known as a ‘stone sucker’ because it sometimes removes stones with its mouth when it wants to make a hollow space in the river bed. It can be found in many fast-flowing deep rivers in England, especially where there is gravel or sand.

The Sea Lamprey is a primitive fish that has no jaws and a circular sucking mouth. It can grow up to metre in length and its upper body is either black or brown with darker mottling. The underside is yellow. It has two fins on its back which are called ‘dorsal’ fins. These fins help the Sea Lamprey to keep balance in the water. It has large reddish coloured eyes and circular rows of sharp hook-like teeth.

The Sea Lamprey is ‘parasitic’ which means it feeds and lives off another animal causing it harm and even death. This eel-like fish uses it round-shaped mouth and sharp teeth to attach itself onto fish such as trout and salmon and then sucks the blood and body fluids out of the fish. The Sea Lamprey can stay attached to a fish for hours, days and even weeks until the fish dies.