Bothriocephalus gregarius is a tapeworm that parasitises the turbot (Scophthalmus maximus).

It has a complex life cycle including two intermediate hosts, a copepod and a small fish.

It lays eggs which pass with the fish faeces out into the sea and which hatch into free-swimming larvae, the coracidium.

If the copepod is then eaten by a small fish, such as a goby, the plerocercoid survives in its digestive tract.

It seems that juvenile turbots feed on copepods, but these crustaceans are too small to form a worthwhile part of the diet of larger turbot, and these bigger fish become infected after feeding on the infected gobies.