Monogenetic flukes are small flukes without a well-developed sucker. At their posterior end, they have a bulbous structure covered with hooks called an opisthaptor. Most monogeneans are ectoparasites on fish or other aquatic animals, although a few live in the urinary bladders of turtles and frogs. Their life cycle involves a single host. Eggs hatch into ciliated larvae, which may attach directly to a host or swim freely for a time before attaching. Adults lack cilia.
Hickman, C.P. and L. S. Roberts. 1994. Animal Diversity. Wm. C. Brown, Dubuque, IA.
Brusca, R. C., and G. J. Brusca. Invertebrates. 1990. Sinauer Associates, Sunderland, MA.
Phil Myers (author), Museum of Zoology, University of Michigan-Ann Arbor.