Life Cycle: Some species of Cosmocephalus utilize an indirect lifecycle where adult worms reside in birds. L1, L2, and infective L3 larvae are found in fishes and amphipods. After the intermediate host is eaten, the parasites molt into L4, L5 and adult stages of the worm inside the esophagus of a bird (Anderson and Wong, 1982).
Systematics are based mostly on complexity of cephalic organs of fixation. Cordons extend longitudinally and expand on the cervical region. Cosmocephalus spp. has cordons recurrent on lateral fields forming simple arch convex anteriorly.
Sources:Anderson, R.C., Chabaud, A.G., and Willmott, S. 2009. Keys to the Nematode Parasites of Vertebrates, Archival Volume, p. 383-387.
Anderson, R.C. and Wong, P.L. 1982. The transmission and development of Paracuaria adunca (Creplin, 1846) (Nematoda: Acuarioidea) of gulls (Laridae). Canadian Journal of Zoology, Vol. 60, p. 1426-1440.