As a multi-cellular creature, the bullfrog is in the kingdom Animalia, also known as Metazoa. Animalia also contains fishes, arthropods, mammals, reptiles and many others.Bullfrogs belong to the phylum Chordates, a group of creatures characterized by having a rod that extends the length of the body.The subphylum is Vertebrata, or the vertebrates and the bullfrog's class is Amphibia, the amphibians including frogs and salamanders.he American bullfrog was classed in the genus Rana from the 1800s to the early 2000s. The breakthroughs that became available to herpetologists in the early 2000s resulted in discovering closer relationships to members of another genus: Lithobates.