Even-Toed Ungulates: Artiodactyla

Because there are as many as 227 species of artiodactyls (ar-tee-oh-DACK-tuhlz), they vary greatly in physical characteristics. The smallest is the mouse deer, which weighs less than 2 pounds (1 kilogram) and stands up to 14 inches (35 centimeters) to the shoulder. The hippopotamus is the largest, weighing in at nearly 10,000 pounds (up to 4,500 kilograms). Head and ear sizes and shapes vary, as do neck lengths, but the eyes are usually big, with long lashes. Tail and leg lengths vary, and fur can be short or long.

Ungulates (UNG-gyuh-luhts) are hoofed mammals. What makes artiodactyls different from perissodactyls (puh-RIH-suh-dack-tuhlz), is the number of toes. With the exception of two species, all artiodactyls have an even number of toes (two or four) on each foot. The hooves are hard and ideal for fast running, though they vary in size depending on the size and mass of the animal. Almost all species have weapons, including horns, antlers, and tusks or canines (the four pointed teeth near the front of the mouth, two on each jaw).

Artiodactyls' coats have two layers: a short underfur and longer guard hairs on top. The top hairs repel water, and the two layers together help control body temperature. Most species have glands that are used for communication. These glands secrete strong-smelling chemicals and substances. The animals use these to mark territory. Animal behaviorists agree that the role of these glands in general is not completely clear.