Aristotle (384-322BCE) first sorted animals as having blood (vertebrates) or not having blood (cephalopods). In the fourth century St. Augustine decided to sort animals as useful, harmful, or superfluous to humans and in the mid-1700s Carolus Linnaeus created the modern hierarchical classification of life.

From Aristotle's time to the mid-1900s there were only two recognized kingdoms (Plantae and Animalia) but once we started using microscopes we discovered many species that didn't easily fit into either kingdom. In the 1800s Ernst Haeckel (1834-1919) proposed a third kingdom: Protista and then in 1969 Robert H. Whittaker (1920-1980) proposed a five kingdom classification (shown above) that's now accepted by most biologists.

The fungi kingdom was created because fungi do not photosynthesize unlike plants and obviously aren't animals. Prokaryotae (Monera) is primarily bacteria because they don't have distinct nuclei and other membranous organelles. Some biologists also separate Prokaryotae into two different kingdoms (Archea and Eubacteria) but generally only the five are used.

Domain: Kingdom: Phylum: Class: Order: Family: Genus: Species