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Introduction to Animal Classification

Taxonomy 101

All living things are divided into seven categories using Latin terms that can be understood worldwide. They progressively get smaller and more numerous, and each contains less living things. Classification of living things is used to help identify different animals and to group them together with their relatives.

The first and largest category is the Kingdom. To date there are five kingdoms: Animalia, which is made up of animals; Plantae, which is made up of plants; Protista, which is made up of protists (single-celled creatures invisible to the human eye); Fungi, which is made up of mushrooms, mold, yeast, lichen, etc; and Monera, which is made up of the three types of bacteria.

The next category is the Phylum. There are several phyla within each kingdom. The phyla start to break the animals (or plants, fungi, etc) into smaller and more recognizable groups. The best known phylum is Chordata, which contains all animals with backbones (fish, birds, mammals, reptiles, amphibians). There is also Arthropoda (insects, spiders, crustaceans); Mollusca (snails, squid, clam); Annelida (segmented worms); Echinodermata (starfish, sea urchins) and many, many more.

The next category that makes up the phyla is the Class. The class breaks up animals into even more familiar groups. For example, the phylum Chordata is broken down into several classes, including Aves (birds), Reptilia (reptiles), Amphibia (amphibians), Mammalia (mammals) and several others.

The next category is the Order. Each class is made up of one or more orders. Mammalia can be broken down into Rodentia (mice, rats), Primates (Old- and New-World monkeys), Chiroptera (bats), Insectivora (shrews, moles), Carnivora (dogs, cats, weasels), Perissodactyla (horses, zebras), Artiodactyla (cows), Proboscidea (elephants) and many more.

Orders can then be broken down into Families. The order Carnivora can be broken down into Canidae (dogs), Felidae (cats), Ursidae (bears), Hyaenidae (hyaenas, aardwolves), Mustelidae (weasels, wolverines), and many more.

The next category is the Genus. The family Felidae, for example, can be broken down into Acinonyx (cheetah), Panthera (lion, tiger), Neofelis (clouded leopard) and Felis (domestic cats).

Finally, the genus is broken down into the Species. The genus Panthera can be broken down to include Panthera leo (lion) and Panthera tigris (tiger). Note that the genus is placed in front of the species.

To complicate things, each category can, in some cases, be broken down into sub-categories. A sub-category is made when there are some animals that are basically the same but live in different areas and behave differently from each other or have some general differences in the anatomy. A prime example is phylum Chordata, class Reptilia, order Squamata. The order Squamata consists of both lizards and snakes because they are basically the same. However, snakes have some physical differences, mainly the lack of legs (although some lizards also lack legs). This warrants the creation of two sub-orders: Serpentes (snakes) and Sauria (lizards). These are then broken down into their own families.

Another example is phylum Chordata, class Mammalia, order Proboscidea, family Elephantidae, genus Elephas and species maximus. Elephas maximus (Asian elephant) is broken down into four sub-species depending on where the sub-species lives and the physical description of it. One example is the Ceylon elephant (Elephas maximus maximus). Note that the sub-species follows the species and that they always receive lower-case letters.

It should be noted that most animals are given common names recognized outside of the scientific community and that these names may be different in each country. For example, in Canada a certain type of spider is known as the daddy long-legs and is known as the harvester spider in the US. Likewise a type of fly in the US is called the daddy long-legs and is known as the crane fly in Canada. However, the Latin term remains the same.

It should lastly be noted that the Latin names of animals are always changing. The Aleutian Canada goose has gone through ten name changes, starting off as the non-sub-species Anser leucopreius and ending with the sub-species Branta canadensis leucopareia. The name will most likely change again in the future if it is decided that the Aleutian Canada goose is an entirely separate species from the Canada goose or if there are no subspecies at all and just the Canada goose.