When attacked the animal bunches up into a ball and digs into the ground, or finds a crevice to protect it s vulnerable under side. Monotremes are the only mammals to lay eggs, but their overall pattern of reproduction is mammalian. Young break through the soft eggshell with an egg tooth. As they grow, teeth regenerate into horny grinding plates that are used to crush their food. Young are fed from mothers mammary glands for 3-4 months.
Individuals start mating at two to three years of age.
An average platypus lives about 10-13 years. The only time echidnas are seen together is during mating season. A single egg is laid into a temporary incomplete pouch. Young become fully independent and move out to occupy their own home range about a year after birth. Longevity is not known in the wild but in captivity life expectancy ranges from 20 to 40 years.