Spirometra is a genus of Pseudophyllid cestode that reproduces in canines and felines but which can cause pathology in humans. As an adult, this tapeworm lives in the small intestine of its definitive host and produces eggs that pass with the animal's feces. The eggs hatch into coracidia which are eaten by copepods which become infected themselves. In the copepod, the worm forms a procercoid, which is infective to vertebrates that ingest them.