Commonly called spiny anteater. Body divisible into head, neck and trunk.
Externally neck and body indistinct and covered with strong pointed spines. Course hair lies at the base of spines. Lower surface has only hairs, no spines.
Head small and produced into a small tubular pointed snout. Head contains paired eyes and nostril.
Eyes small, without nictitating membrane. External ears absent. Tongue long and sticky and teeth absent in adult.
Girdles forelimbs and hind limbs reptile-like. Feet without web. Sharp claws used for digging the earth and nests of insects.
Second digit of hind limb has a long and curved toilet claw to clean spines. Tarsus of male has grooved horny poison spur.
Male ale possesses mammary glands secreting milk and this condition is called as gynaecomastisus. where both parents nourish young one. Teats absent.
Mammary glands open inside a ventral abdominal pouch by several apertures. Eggs transferred by mother into the pouch where the young are nourished with milk.
In defensive position Echidna rolls in such a manner that bilateral barrier of spines completely covers it.

SPECIAL FEATURES

Echidna has phylogenetic significance, as it serves a link between reptiles and mammals. The animal is specialized for ant eating. The jaws are pointed forming a rostrum devoid of any teeth. Tongue is protrusible. The posterior region of the tongue is serrated to grind insects and the secretion of salivary gland neutralizes formic acid of ants.