The short-beaked echidna and the duck-billed platypus are the two mammals that lay eggs. The echidna resembles a porcupine, but it is a completely different animal.
The echidna has spines all over its body along with short fur. The short-beaked echidna is the cousin of the long-beaked mammal, and it is much smaller in size. The average weight of a short-beaked echidna is anywhere from 5-15 pounds. Found throughout Australia, the mammals live alone and typically only spend time with other echidnas during mating season, which occurs in the summer months. After mating, the echidna begins growing a pouch in its stomach which holds the egg after it is laid. After a week and a half, the egg hatches, and the baby echidna emerges. It then stays in the pouch for slightly less than 2 months before the female removes it and places it in a nest or burrow.
The other egg-laying mammal, the duck-billed platypus, is foundthroughout Australia and Tasmania. They live near water and grow to reach around 5 pounds. These mammals mate in the water, and after mating takes place, the female has a gestation period of around 30 days. It then lays the eggs, which incubate for around 10 days. Two to three eggs are often laid at once, and the mother keeps them close to its body using its tail.