procercoid

The procercoid penetrates the gut wall and enters the muscles or connective tissues.

The procercoid then develops into the plerocercoid.

In the copepod, the worm forms a procercoid, which is infective to vertebrates that ingest them.

The coracidium then sheds its ciliated epithelium, penetrates the midgut wall of the copepod, and develops into the infective procercoid after 18 days.

The procercoid probably parasitizes copepods, which are eaten by the second intermediate hosts: teleost fishes, decapods or cephalopods, which may also serve as paratenic hosts.

Once the infected copepods are eaten by the fish hosts, the procercoid rapidly transform into the plerocercoid stage and attaches to the intestinal gut wall, where it develops into the adult parasite over the course of 21-23 days.

When the free-swimming larvae, called coracidia, are eaten by copepods (intermediate host), it penetrates into the gut wall, travels to the coelom, and develops into a second larval stage called a procercoid (infective form) all within 6-10 days.