Final answer:
Earthworms belong to the phylum Annelida, which includes true, segmented worms found in various habitats. Flukes, however, are part of Platyhelminthes and are classified under the Trematoda class.
Step-by-step explanation:
To which phylum do earthworms belong? Earthworms belong to the phylum Annelida. This phylum contains true, segmented worms including earthworms, polychaete worms, and leeches. This diverse group of animals can be found in marine, terrestrial, and freshwater habitats, though moisture is critical for those living on land. Notable features of annelids include their segmented body structure, known as metamerism.
As for flukes, they are classified within the phylum Platyhelminthes, which consists of flatworms, including medically important parasites like flukes and tapeworms. The flukes specifically belong to one of the classes within Platyhelminthes known as Trematoda.