Microbiology, 2021

5.2 • Parasitic Helminths 195
Figure 5.20 Phylum Platyhelminthes is divided into four classes. (a) Class Turbellaria includes the Bedford’s flatworm (Pseudobiceros
bedfordi), which is about 8–10 cm long. (b) The parasitic class Monogenea includes Dactylogyrus spp. Worms in this genus are commonly
called gill flukes. The specimen pictured here is about 0.2 mm long and has two anchors, indicated by arrows, that it uses to latch onto the
gills of host fish. (c) The Trematoda class includes the common liver fluke Fasciola hepatica and the giant liver fluke Fascioloides magna
(right). The F. magna specimen shown here is about 7 cm long. (d) Class Cestoda includes tapeworms such as Taenia saginata, which
infects both cattle and humans and can reach lengths of 4–10 meters; the specimen shown here is about 4 meters long. (credit c:
modification of work by “Flukeman”/Wikimedia Commons)