It is one of the most primitive mammals in existence. It lives all over Australia and hibernates when it is cold. Its body temperature is constant.

The echidna has hard spines and no teeth in its mouth. It looks like a hedgehog. The echidna has a long tubular mouth, its nostrils open at the mouth, its tongue is long and sticky, and it feeds on termites and ants. Strong limbs, powerful claws on each toe, long and sharp claws, which can be used for digging and digging ant nests.

The short and sharp thorns on the echidna are its amulet, but these thorns will not grow firmly on the body. When encountering an enemy, the echidna will curl up into a ball or disappear quickly in loose soil, or shoot thorns at the enemy like an arrow. The echidna can dig holes at an amazing speed and bury itself in the soil.

2 porcupine porcupine, also known as porcupine, is a rodent covered with spikes, which can be used to defend against predators. Porcupines come in brown, gray and white. The spines of different porcupine breeds have different shapes, but they are all hairy, and there is a layer of keratin on the surface, embedded in the muscle tissue of the skin. The thorns of the old world porcupine (porcupine family) are bundle-shaped, while the thorns of the new world porcupine (porcupine family) are mixed with hair. The porcupine's thorn is very sharp and easy to fall off, which will pierce the attacker. Their spines are barbed and can be hung on the skin, which is difficult to remove.