''Ligula intestinalis'' is a

tapeworm Eucestoda, commonly referred to as tapeworms, is the larger of the two subclasses of flatworms in the class Cestoda (the other subclass being Cestodaria). Larvae have six posterior hooks on the scolex (head), in contrast to the ten-hooked Ce ...

of fish, fish-eating birds and

copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...

s, with species from each group featuring in its complex

life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from conception to reproduction *Life-cycle hypothesis, in economics *Erikson's stages of psy ...

. It is a parasite that changes its intermediate host's behavior to become more vulnerable to its predators. In this case, it uses copepods and cyprinid fish as their intermediate host and develops inside of them to get to its final destination which is fish-eating birds. Plerocercoids, ''Ligula intestinalis'' larvae, influence secondary intermediate hosts’ behavior, health, and fecundity. Additionally, this species can cause the gonads of fish to remain undeveloped.

References

Cestoda {{Cestoda-stub