英语（英文）版动物世界（动物介绍）.ppt

Introduction to Animals
Characteristics
anization
Heterotrophic
Sexual reproduction and development
Movement
Animal Classes
An animal class is made up of animals that are all alike in important ways. Scientists have grouped animals into classes to make it easier to study them.
There are many different animal classes and every animal in the world belongs to one of them. The five most well known classes of vertebrates (animals with backbones) are mammals, birds, fish, reptiles, amphibians.  They are all part of the phylum chordata -- I remember "chordota" by thinking of spinal chord.
There are also a lot of animals without backbones.  These are called invertebrates and are part of the phylum arthropoda (arthropods).  Two of the monly known classes in this phylum are arachnids (spiders) and insects.
mals/
Mammals
People are mammals. So are dogs, cats, horses, duckbill platypuses, kangaroos, dolphins and whales. What do all these animals have mon, you ask?
The answer is – MILK! If an animal drinks milk when it is a baby and has hair on its body, it belongs to the mammal class
Mammals are one of the 6 main classes of animals.  Animal classes are groups of animals that scientists consider to be alike in some important ways.  Mammals are the animal class that people belong to.  
There are only about 4,000 kinds of mammals. Warm-blooded
Birds
Birds are animals that have feathers and that are born out of hard-shelled eggs.
Some people think that what makes an animal a bird is its wings. Bats have wings. Flies have wings. Bats and flies are not birds. So what makes an animal a bird?
The answer is feathers!
All birds have feathers and birds are the only animals that do. The feathers on a bird’s wings and tail overlap. Because they overlap, the feathers catch and hold the air. This helps the bird to fly, steer itself and land.
Fish
Fish are vertebrates that live in water and have gills, scales and fins on their body.  There are a lot of different fish and many of th