BIO 203


 Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivoria
Family: Ursidae
Genus: Ursus
Species: Ursus arctos

The grizzly bear is in the domain Eukarya. It is classified in this domain because it is a Eukaryote. All Eukaryotes have cells, a nucleus, and other membrane bound organelles (Wallace, 1997).

They are in the kingdom Animalia because they are eukaryotic, multicellular, heterotrophic, motile, and they lack rigid cell walls (Wallace, 1997).

They are in the phylum Chordata because they are deuterostomes (develop anus-first) and they possess a notochord and a tail (Wallace, 1997).

Grizzly bears are in the class Mammalia because they have hair, three middle ear bones, sweat glands (and mammary glands if they are females), a four-chambered heart and a neocortex. The neocortex is a portion of the brain located in the outer layers of the cerebral cortex involved in reasoning, sensory perception, thought and language (Wallace, 1997).

They are in the order Carnivoria because they are flesh-eating organisms with sharp teeth and claws (Wallace, 1997).

They are in the family Ursidae because they are caniforms (dog-like carnivorians) with long snouts and non-retractile claws (Wallace, 1997).

They are in classified in the genus Ursus, because they are a type of bear with large bodies, long hair, and short legs and tails (Wallace, 1997).

Ursus arctos
The scientific name for the grizzly bear, Ursus arctos, comes from the Latin word, ursus, meaning bear and the Greek word, arctos, also meaning bear (Wallace, 1997).


     The closet relative to the grizzly bear is the polar bear. The grizzly and the polar bear are sister taxa. Sister taxa simply mean that they are the closest living relatives of each other. The phylogenetic tree below is based on the Ursidae family. The members of the Ursidae family are all caniforms, as stated earlier. Polar bears recently diverged from grizzly bears, approximately 4-5 million years ago (Phylogeny, 2011).

Marissa Hogan


     The next tree shows the phylogeny of the order Carnivora. This tree shows that the Ursidae are most closely related to the Canidae. Members of the Canidae include domestic dogs, wolves, foxes, jackals, and coyotes (Westbroek, 1998).


Marissa Hogan

Habitat and Geography