https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1897&context=parasitologyfacpubs

Synopsis of freshwater crayfish diseases and commensal organisms

Diseases of crayfish: a review

Publisher Summary The life cycles of virtually all the adult cestodes, nematodes, and acanthocephalans are complex and require one or two intermediate hosts, of which the second in some instances is a fish, followed by the final development to sexual maturity and egg or larval release in the definitive fish host. The chapter focuses on the schemes of classification adopted and reports the seasonal studies of the cestode, nematode, and acanthocephalan adults of various species. The seasonal information is related to the major climatic zones of the world— namely, tropical, subtropical, mid-latitude, polar, and mountain. It is noted that there is a scarcity of information about seasonal patterns of occurrence of helminths of freshwater fishes in the tropical parts of the world. The chapter considers the complexities of the seasonal dynamics involved in the life cycles of the helminth species. The study of seasonal dynamics of occurrence of fish parasites leads naturally to the wider aspects of the concepts determining the population biology of host-parasite systems.

Seasonal Occurrence of Helminths in Freshwater Fishes Part IV. Adult Cestoda, Nematoda and Acanthocephala

This report is a summary of the published records of parasites found from the marine and estuarine fishes of California, Oregon, and Washington. Coverage has not been limited to the western United States, but rather includes parasite reports from throughout each fish's range. Included is a host-parasite list and parasite-host crossindex.

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A Checklist of Parasites of California, Oregon, and Washington Marine and Estuarine Fishes

4 – Metazoan Symbionts of Crustaceans

The life history of Neoechinorhynchus rutili (Mueller, 1780) was demonstrated experimentally. Shelled embryos are released by the adult worm into the lumen of the digestive tract of freshwater fishes and subsequently pass out with the feces. These "eggs" are ingested by ostracods (Cypria turneri). Within the intestine of the ostracod the acanthor hatches, penetrates the wall of the intestine, and in 6 to 12 days is found free in the hemocoel where it metamorphoses through the acanthella to the juvenile stage in 48 to 57 days. This stage is infective to the fish. The development in the ostracod has been followed and comparisons have been made with the other two species of the genus which have been studied. Neoechinorhynchus rutili (Mueller, 1780), an acanthocephalan worm parasitizing the small intestine of freshwater fishes, was redescribed by Van Cleave (1950). He showed its distribution to be continuous throughout the northern Holarctic Region, including Sweden, Finland, Russia, central Europe, Wisconsin, within the Arctic Circle of the Canadian Northwest Territories, off the coast of Alaska, and into Washington. The adult worm is found in 14 families of fishes: Salmonidae, Thymallidae, Cyprinidae, Catastomidae, Cobitidae, Esocidae, Gadidae, Gasterosteidae, Centrarchidae, Percidae, Labridae, Gobiidae, Cottidae, and Zorarcidae (Golvan, 1959). Van Cleave implied that occurrence of adults in frogs and turtles is probably due to accidental infections (1950). Life history studies on N. rutili have been sparse and incomplete. Robin (1870) found a worm in the leech Nephelis octoculata which Received for publication 23 August 1963. * This investigation was supported in part by research grant AI-00867 from the National Institute of Allergy and Infectious Diseases, U. S. Public Health Service and by the Oregon State Game Commission. Published with the approval of the Oregon State University Monographs Committee. Research Paper No. 460. t Present address: Department of Zoology, University of Wisconsin, Madison. was identified from his woodcut by Villot (1885) as Echinorhynchus clavaeceps (= N. rutili). In 1885, Villot reported finding E. clavaeceps encysted in the adipose tissue of the larvae of Sialis niger. Finally, in a research note Levander (1905) mentioned finding larvae in ostracods, but he neglected to record the genus and species. The early embryology of Neoechinorhynchus rutili has been studied in detail by Meyer (1931). He traced the cleavage and cell lineage up to the development of the shelled acanthor, which is shed by the adult female and is infective to the intermediate host. No study has been made of the complete development in the intermediate host. There have been, however, a few developmental studies carried out on other species of Acanthocephala. The scattered observations made prior to 1940 have been discussed by Ward (1940). Hynes and Nicholas (1957) brought together subsequent observations in their work on Polymorphus minutus. Moore (1962), in his study of Mediorhynchus grandis, pointed out the need for more information about the acanthor types and their development to aid in establishing phylogenetic relationships. The present study was undertaken to determine experimentally the life cycle in local hosts and to describe the development in the

Sheridan V. Merritt

Papers

The life history of neoechinorhynchus rutili and its development in the intermediate host (acanthocephala: neoechinorhynchidae).