* Eels are fish: They belong to the order Anguilliformes, which includes a wide variety of elongated, snake-like fish.
* Worms are invertebrates: They lack a backbone and are typically segmented. Eels, however, have a bony skeleton.
While eels share some physical similarities with worms, they are classified as fish due to their internal structure, respiratory system (gills), and other biological characteristics.