The Life Cycle of Diphyllobothrium oblongatum Thomas, a Tapeworm of Gulls

Abstract

This investigation deals primarily with the life cycle of a pseudophyllidean tapeworm infecting young gulls from Lake Michigan. It also examines the possibility of using larval characters as well as adult characters in establishing spp., especially in the genus Diphyllobothrium. Eggs from shed proglottids hatch coraci-dia in 6 days or more weeks depending upon temp. Freezing of eggs solid in ice does not destroy their ability to hatch. Developing eggs may pass through the intestines of guppies unharmed. Coracidia may hatch from eggs kept 2 or more years in a refrigerator. The procercoid develops to the infective stage in Diaptomus oregonensis in 2 weeks or more depending upon temp. Typical plerocercoid cysts formed in guppies in 135 days after the fish had fed upon infected cope-pods. Similar cysts from natural infections in ciscos, Leucich-thys artedi, fed to laboratory reared gulls, Larus argentatus and L. delawarensis, developed to adult worms in 3 1/2[long dash]\ weeks after which they were shed. After the initial infection during the 1st week, additional feedings of cysts in subsequent weeks did not increase the worm burden.