Unit 3 Lesson 2 What Are Some Animal

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Life Cycles • All animals reproduce, or have young, but not in the same way. • Birds and some fish, reptiles, and amphibians lay eggs. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Life Cycles Other animals, such as mammals, give birth to live young. Copyright © Houghton Mifflin Harcourt Publishing Company

Who is this?

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Frog Life Cycle • A tadpole is an immature frog that must live in the water. It hatches from an egg. • It has gills and a tail. It breathes and swims like a fish. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Frog Life Cycle • After about five weeks, the tadpole starts to change. Tiny buds beside the tail grow into little hind legs. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Frog Life Cycle Then, as a tadpole, the young frog develops four legs. Its tail will soon disappear and its lungs are almost completely developed. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Frog Life Cycle Finally, the frog has fully developed lungs and legs. It’s an adult! Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Frog Life Cycle Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Frog Life Cycle • As a frog develops, its entire appearance changes. • Metamorphosis is a major change in the body form of an animal during its life cycle. • A frog goes through a series of changes after it hatches as a tadpole. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Insect Life Cycles • Most insects undergo metamorphosis as they develop into adults. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Insect Life Cycles • In the second stage of complete metamorphosis, the insect larva hatches from its egg. • During the third stage of complete metamorphosis, the larva becomes a pupa. The insect does not move as it slowly changes into an adult. • In both of these stages, the insect looks very different from the adult. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Insect Life Cycles • Some insects, such as grasshoppers, go through incomplete metamorphosis. • After they hatch from eggs these insects look very much like the adults. They also go through changes as they grow, but they way they look does not change. • Grasshoppers get bigger and grow wings as they reach adulthood. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 3 Lesson 2 What Are Some Animal Life Cycles? Why It Matters Diversity • Every living thing is different. Even young that have the same parents are not the same. • Diversity — different characteristics — is what makes everyone different from one another. • Think about a family of dogs. Even though they have the same parents, each puppy might have different colored fur. They get different features from each parent. Copyright © Houghton Mifflin Harcourt Publishing Company