Which of the following groups is the correct classification for flukes?

• A. Nematode
• B. Trematode
• C. Acanthocephalan
• D. Cestode

Answer: (B)

Flukes are trematodes, a type of parasitic flatworm with a leaf-like, dorsoventrally flattened body and attachment organs, typically an oral sucker and a ventral sucker (acetabulum). Their life cycles are often complex, usually involving a snail as an intermediate host and a vertebrate as the final host. This combination of body plan and reproductive/attachment features is distinct from other parasite groups: nematodes are roundworms with a tubular body and a complete digestive system; cestodes (tapeworms) are long, segmented worms that attach with a scolex and lack a true digestive tract; acanthocephalans have a thorny proboscis used to attach to the host. Because of these characteristics, flukes are best classified as trematodes. Examples include liver flukes and blood flukes.