Surprising Animals That Lay Eggs

The mammalian species is best known for giving birth to live young, but did you know that certain mammals lay eggs? While all birds and some reptiles lay eggs, a select few mammals do too. These egg-laying mammals are found mostly in Australia and New Guinea, along with a few other places around the world. While everyone thinks of birds when thinking of creatures that lay eggs, the mammals that do so have fascinating and unique adaptations.

Types of Egg Laying Mammals

The only mammals that lay shelled eggs are known as monotremes and are found in Australia and New Guinea. Monotremes are polyprotodonts, which means they have several front teeth and primitive jaw joint structures that allow them to hold onto suckling prey like insects. The five species of monotremes that lay eggs are the platypus, echidnas, short-beaked echidnas, long-beaked echidnas, and spiny anteaters.

The platypus is the only mammal that lays leathery and soft eggs that most closely resemble fish eggs. Echidnas and short-beaked echidnas lay leathery eggs that are much harder. Long-beaked echidnas and spiny anteaters lay eggs that are leathery on the outside and hard on the inside. All of these eggs are about the size of a grape and take about 10 days to hatch.

Adaptations for Laying Eggs

Monotremes have some special adaptations that allow them to lay eggs. The reproductive systems of monotremes are primitive and simpler than other mammals, so they have not fully evolved the ability to give live birth like marsupials or placental mammals. To make up for that, monotremes have developed some interesting aspects of egg laying.

For example, monotremes have a cloaca, which is an opening used for excretion and reproduction. This makes it possible for these creatures to lay eggs without the assistance of a womb. Additionally, these mammals have an egg tooth, which helps platypuses break out of their eggs at hatching. Their urinary and genital systems are also fused together so they can excrete waste and lay eggs without having separate systems.

Conclusion

Although most mammals give live birth, there are five types of mammals that lay eggs – platypuses, echidnas, short-beaked echidnas, long-beaked echidnas, and spiny anteaters. They have some unique adaptations like a cloaca, a fused U.G. system, and an egg tooth which helps them to lay eggs in a process called oviparity. It is truly an amazing example of how much diversity there is in the animal kingdom.