Equids inhabit the desert and grasslands of Asia and Africa but have been introduced to many areas around the globe. All species of equids have a heavy coat of fur, feed primarily on grass, and possess acute senses of sight and hearing.
The domesticated horse is descended from the wild horse. Domesticated horses are the most common equids today. Most equids in the wild are endangered as a result of habitat destruction.
Equids form herds that consist of extended family groups. These herds cover large areas and individuals communicate to other herd members using mouth gestures, ear movements, vocalizations, and tail movements.
Horses and their relatives are referred to as odd-toed ungulates. Ungulates is a term used to described hoofed animals. Hoofed animals are categorized by the number of toes they posess (an even number or odd number). In the case of horses, they posess an odd number of toes.
Horse Classification
Horses and their relatives (Family Equidae) are mammals, which means they possess the basic characteristics of all mammals which include:
- mammary glands
- hair
- diaphragm
- three middle-ear ossicles
- heterodont dentation
- sweat, sebaceous, and scent glands
- four-chambered heart
- large cerebral cortex
Additionally, equids belong to the Order Perissodactyla (odd-toed ungulates) which is a group of mammals characterized by having hooves. In addition to equids, the Order Perissodactyla includes tapirs and rhinoceroses. The taxonomic classification of horses is as follows:
- Kingdom: Animalia
- Phylum: Chordata
- Class: Mammalia
- Order: Perissodactyla
- Family: Equidae
Within the Family Equidae there is one genus (Genus Equus) which contains eight species and numerous subspecies:
- Onager (Equus hemionus)
- Grevy's zebra (Equus grevyi)
- Mountain Zebra (Equus zebra)
- Plains Zebra (Equus quagga)
- Burchell's zebra (Equus burchellii)
- Domesticated Horse (Equus caballus)
- Donkey (Equus asinus)
- Kiang (Equus kiang)
- Przewalski's wild horse (Equus caballus przewalskii) *
- Tarpan (Equus caballus gmelini) *
- African wild ass (Equus asinus somalicus) *
* Indicates subspecies.
Terminology
Below is a collection of specialized words (and links to their definitions) that are commonly used to describe various aspects of horses such as their behavior, evolution, anatomy, and adaptation:
