General terms:
* Taxonomic groups: This is the most accurate, as it refers to the hierarchical system used to classify living things.
* Categories: This is a more general term, but it can be used to describe any grouping, including classes.
* Classifications: This is another general term, similar to categories.
* Phyla (singular: phylum): This is a higher-level classification than class, but it's often used to refer to distinct groups of animals.
More specific terms:
* Mammalia: This is the class that includes all mammals.
* Aves: This is the class that includes all birds.
* Reptilia: This is the class that includes all reptiles.
* Amphibia: This is the class that includes all amphibians.
* Pisces: This is the class that includes all fish.
* Insecta: This is the class that includes all insects.
You can also use phrases like:
* Animal kingdom
* Different animal types
* Groups of animals
The best word or phrase to use depends on the specific context and what you are trying to convey.