Groups of Animals

1. The two main groups of animals are the vertebrates and the invertebrates.
    

2. These can be divided into smaller sub groups.
    

3. Biologists have to think very carefully about the reasons for grouping animals.

Movement and Feeding

1. Animals move for various reasons, including feeding and escaping from predators.
    

2. Nearly all animals belong to one of the following types: herbivores, carnivores and omnivores.
    

3. Animals can move in one or more different ways. The various types of movement are walking, running, leaping, hopping, slithering, burrowing, swimming and flying.

Movement on Land

1. Animals which move on land can walk, run, leap, hop or slither.
    

2. All vertebrates have a skeleton made of bone inside their bodies. The skeleton is able to move because of its joints and muscles.
    

3. Arthropods also have a skeleton but it is on the outside of their bodies. It is made of chitin, not of bone. Their muscles are inside the hard skeleton. 

Movement in the Air

1. Nearly all birds fly and many insects fly. The bat is a flying mammal.
    

2. Flying animals have wings which are moved up and down by the action of muscles.
    

3. The bird's skeleton is adapted to help it fly. Its body is covered with feathers which also help it to fly through the air.
    

4. Flying insects have muscles inside the skeleton which move their wings. They have either one or two pairs of wings.
    

5. Some other animals are able to glide through the air. The 'flying' fish and the 'flying' squirrel are really gliders. They do not have any wings to beat.

Movement in the Water

1. Fish are adapted for swimming by having a streamlined shape and fins.
    

2. Most mammals which spend a lot of their time in water have also developed a streamlined shape. They also have flippers to help them move through the water.
    

3. Many water insects have one pair of legs shaped like paddles to push them through the water.
    

4. Other animals, such as birds and frogs, have webbed feet which act as paddles.
   

Recognizing and Choosing Food

1. Animals use one or more of their senses to find their food. These senses are sight, hearing, touch, smell and sensitivity to heat.
    

2. Some animals only eat one kind of food whereas others have a more varied diet.
    

3. Certain animals can eat a variety of food but prefer one type of food to others.
    

4. The diet of some animals will depend on the season.

How Animals Feed

1. Carnivores need to be able to catch and kill their prey before they can eat it. Different carnivores deal with this problem in different ways.
    

2. Carnivorous mammals, such as the cat and dog, have teeth which are specially adapted to help them kill their prey and to tear meat.
    

3. Herbivores do not have to ‘catch’ their prey but they have a different problem. Vegetation is tough and needs a lot of chewing to break it down into small pieces. Herbivores have mouthparts which are adapted to this.
    

4. Herbivorous mammals have large back teeth with wide surfaces. The vegetation is chewed between the top and bottom teeth. The ruminants chew their food twice.
    

5. Some omnivores are filter feeders, feeding on plankton which is a mixture of microscopic plants and animals.
    

6. A few carnivores and herbivores feed only on liquids. They have mouthparts especially adapted to suck their liquid meals.

How Food is Digested

1. When food is taken into the body it is ingested, digested and absorbed. the non-digestible food is eliminated.
    

2. The absorbed food is moved to all parts of the body by the blood. Among other things it provides energy for the body's activities.
    

3. For a balanced diet humans must eat foods containing the following chemicals : carbohydrates, lipids, proteins, vitamins, minerals and water.
    

4. Energy is measured in kilocalories or kilojoules.