In this topic you will learn how animals develop and reproduce.

The stages of growth and change for an animal make up the animal's life cycle. Each organism has its own particular life cycle. However, all organisms follow the same general pattern of birth, growth, reproduction, and death.

The life span of an animal is how long it can be expected to live. The life span of a human is about 78 to 80 years. Scientists aren't sure what determines an animal's life span. They think cell division may control how long an animal lives. Throughout an animal's life, its cells divide many times. After many divisions, cells get damaged. Older animals have more damaged cells than younger animals. Therefore, older animals are more likely to develop diseases that weaken them.

Most young animals look like smaller copies of their parents. Certain animals go through changes during development. This is called metamorphosis. Metamorphosis is a process of changes during an animal's development.

The life cycle of every animal includes reproduction, the making of new animals. There are two types of reproduction. In asexual reproduction, offspring are produced by only one parent. In sexual reproduction, offspring are produced by two parents. In animals, sexual reproduction is more common than asexual reproduction. Sexual reproduction requires two parents.

The passing of traits from parent to offspring is called heredity. Offspring inherit traits from both parents. The offspring ends up with a mixture of traits. Some traits come from the father. Other traits come from the mother.

Knowing about life cycles can help you identify some of the problems and opportunities that lie ahead in your life. With this knowledge, you can plan a better future.