Why animal can walk the day it is born?

No. To begin with, baby echidnas are not born - they are hatched. During the breeding season, a female echidna develops a rudimentary pouch - just a flap of skin - on its abdomen. The female echidna manages to lay a single egg in its pouch, and incubates the egg there for ten days. When the young hatches, it is fed on mother's milk which seeps from milk glands, not teats like other mammals. It is dependent on this milk, and it stays in the mother's pouch for two to three months. The young is transferred to a burrow as its spines grow, and it remains in the burrow for another three to four months.