This group of flukes has few features in common, and while many of its adults have quite distinctive morphology and life cycles, there is tremendous diversity within the group.

Life Cycle

Life cycles are diverse. Usually the final larval stage in the mollusc is a sporocyst, but some groups produce rediae as well. In all cases the cercariae which emerge from the mollusc first intermediate host swim and penetrate the next host in the cycle, which may be a second intermediate host or the definitive host. Thus these species all undergo a tissue migration in a vertebrate host at some point in their lives. The metacercariae take on a number of unusual forms, such a diplostomulum, neascus, tetracotyle, and schistosomule.


One of the common features of the group is the presence of cercariae with a furcocercous tail. Adults are more diverse, and in fact many taxonomic keys to the Digenea simply provide keys to the various families and not to higher-level taxa. A few groups are readily recognizable such as one in which adults have a division into fore- and hind-body regions, or others in which there is even a division into male and female forms.