Invertebrate Zoology: A Study Guide - T. A. Dauda 2014

Multicellular Animals
Flatworms
Pathogenic Cestodes - Order Pseudophyllidea

This order includes one of the most dangerous fish parasites — the common tapeworm (Ligula intestinalis). In fish, the tapeworm is found in the large plerocercoid stage (50-80 cm), lying as a tangle of ribbons in the body cavity of bream, roach, and other cyprinid fish. The adult stage of the tapeworm, only slightly larger than the larva, lives in the intestines of fish-eating birds.

The broad tapeworm (Diphyllobothrium latum) parasitizes the small intestines of humans and various fish-eating mammals, forming chains of 3-4 thousand segments, and can exceed 10 m in length (Fig. 18). In its sexually mature state, it inhabits the intestines of humans and carnivorous animals. There are 2 intermediate hosts: the first are copepods (cyclops and diaptomus), and the second is fish, primarily pike (Fig. 19). They are widely distributed in Europe and Asia, and now also in North America.

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Fig. 19 Life Cycle of the broad tapeworm (Diphyllobothrium latum)



Last update: 13/08/2026

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