Echidnas: Tachyglossidae

Echidnas (ih-KID-nahz), also called spiny anteaters, are solidly built, short-legged, shuffling mammals that can grow fairly large, up to 14 pounds (6.5 kilograms) for the short-beaked (or short-nosed) echidna and up to 20 pounds (9 kilograms) for the long-beaked (or long-nosed). Head and body length in an adult short-beaked echidna can reach 21 inches (53 centimeters), the stubby tail adding another 3.5 inches (9 centimeters). Head and body length in adult long-beaked echidnas gets as long as 30.5 inches (77.5 centimeters), and the tail, like that of the short-beaked echidna, is a mere stubby shoot. Male echidnas are larger than females. Although echidnas may look overweight, most of the soft tissue mass that might be mistaken for blubber is muscle, lots of it.

The two species look similar but some differences are obvious, especially the snout, which is made of bone, cartilage, and keratin (what claws and fingernails are made of). The snout is shorter and straight or slightly upturned in the short-beaked echidna, but longer, thinner, and downcurving, like the bill of a nectar-sipping bird, in the long-beaked echidna. An echidna's head is small and the neck is not obvious, so that the head seems to flow directly into the body.

Echidnas have full coats of brown or black hair, with scattered, hollow spines, which are really modified hairs, studding the body on the back and sides. The spines are yellow with black tips in some animals, and up to 2.4 inches (6 centimeters) long. In short-beaked echidnas, the spines are longer than the fur, so that the spines are noticeable, but the coat of the long-beaked echidna is just the opposite: the fur is long enough to cover most of the spines.

The four legs are short, with powerful muscles and claws, proper for an animal that frequently digs in the soil and tears open logs and termite mounds. The hind feet point backwards, and are used to push soil away and out when the animal is burrowing.