Life Cycle: "Species of Capillaria can have either direct or indirect lifecycles. For example, C. philippinensis is indirect and uses fish for the L3 infective larvae and mammals and birds and the definitive host. C. hepatica has a direct lifecycle parasitizes rodent livers. Eggs are released into the environment when the animal dies or is eaten. The egg embryonates and is consumed by the new host where the parasite migrates to the liver and develops and produces eggs" (Center for Disease Control).
"C. aerophila is a lungworm that has a direct lifecycle infecting dogs and other carnivores. The eggs are produced in the lungs, coughed up, and then swallowed to be passed through the feces. Reinfection occurs when the eggs are consumed by the new host through food or water" (Merck vet manual).
Body capillary; mouth simple, with bacillary bands or not. Esophagus long, gradually increasing in size posteriorly; stichosome very prominent. Male with terminal or subterminal anus; usually small membranous caudal alae or bursa-like structure present; spicule long and slender, with spinose or smooth sheath. Female with vulva near posterior end of esophagus; oviparous, eggs elliptical, with polar plugs. Parasites of digestive tract, liver, or urinary bladder of vertebrates.
Sources: Hoffman, G.L. and Williams Jr., E.H. 1999. Parasites of North American Freshwater Fishes, Second Edition, p. 268.
Biology - Life Cycle of Capillaria philippinensis. Centers for Disease Control and Prevention.
Biology - Life Cycle of Capillaria hepatica. Centers for Disease Control and Prevention.
Merck vet manual.