Egg (biology)

From Simple English Wikipedia, the free encyclopedia

For the female reproductive cell, see Ovum.

An egg is what surrounds the zygote of some animals that do not birth living babies.

Some animals, mostly mammals, keep the zygote inside their body where it grows until it is ready to be born. Some animals do not keep the zygote in their bodies, but lay an egg in which the zygote is. The egg nourishes and protects the embryo. When the baby animal is ready, it hatches, that means it comes out of the egg.

Egg-laying animals are most fish, reptiles, amphibians and birds. Monotremes are the only mammals that lay eggs. Most insects and arachnids also lay eggs.

The Ostrich has the largest eggs of all currently living animals.

Eggs, mostly bird eggs, are also often eaten as food.


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