Tongue worms have three larval stages. The first stage develops
within the eggs in a herbivorous intermediate host. Rabbits
are the main intermediate hosts for Linguatula; fish are intermediate
hosts for crocodile pentastomes. Second-stage larvae hatch
from the eggs in the stomach of the herbivore; they swim and
bore with their mouths into the lungs or liver or into the linings
of these host organs. In the tissues of the intermediate host, the
larvae enter a third stage: they encapsulate to form cysts. It is
possible that the cysts are digested when the herbivore host is
eaten by a carnivore, and that the pentastome then moves with
its hooks from the carnivore’s stomach into its nasal or lung passages.
However, there is evidence that the pentastome leaves its
cyst while it is still in the carnivore’s mouth. In either case, the
adults embed themselves in the nasal sinuses or lung tissue, they
mate, and the cycle begins again.
Tongue worms have three larval stages. The first stage develops
within the eggs in a herbivorous intermediate host. Rabbits
are the main intermediate hosts for Linguatula; fish are intermediate
hosts for crocodile pentastomes. Second-stage larvae hatch
from the eggs in the stomach of the herbivore; they swim and
bore with their mouths into the lungs or liver or into the linings
of these host organs. In the tissues of the intermediate host, the
larvae enter a third stage: they encapsulate to form cysts. It is
possible that the cysts are digested when the herbivore host is
eaten by a carnivore, and that the pentastome then moves with
its hooks from the carnivore’s stomach into its nasal or lung passages.
However, there is evidence that the pentastome leaves its
cyst while it is still in the carnivore’s mouth. In either case, the
adults embed themselves in the nasal sinuses or lung tissue, they
mate, and the cycle begins again.
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