Name ____________________________
What is an Animal?
That might seem like an odd question, but if we are going to classify them, we really ought to
decide if they belong in the animal group in the first place. Animals are living organisms. This
means they breathe, they eat, they grow and they reproduce (make more like themselves).
Plants are living organisms, too. So, what is the difference between a plant and an animal? The
biggest difference is that most plants do not move, whereas most animals do. The true
difference, though, is that plants produce their own food, whereas animals feed off other
things.
Bones or No Bones?
Once you have decided you have an animal, you need to decide where to put it. The Animal
Kingdom is divided up into groups. Every animal belongs in a special place, sort of like an address.
The first two groups are the vertebrates and invertebrates. The invertebrates are animals with
no bones. These include insects, spiders, and other groups for things like crabs, jellyfish,
oysters, earthworms and more. The vertebrates, or animals with bones, can be divided into five
main groups. These are mammals, birds, fish, reptiles and amphibians.
Invertebrates (no bones)
We are only going to look at two groups of invertebrates. Spiders and insects. Many people
thing that spiders are insects, but they are wrong.
Insects have three main body parts and six legs.
Spiders have two main body parts and eight legs.
Vertebrates (have bones)
There are five main groups. These groups can be split further, into warm-blooded and coldblooded animals. A warm-blooded animal is like you and me. It keeps its body temperature the
same, unless it is sick. Cold blooded animals don't keep their body temperatures the same, it
changes according to the surroundings. So if the weather is hot, the animal is hot, and if the
weather is cold, it is cold.
Warm-blooded:
Mammals:
Have hair or fur
Breathe air
Feed their young milk
Whiskers are a type of hair, so just having whiskers counts as having hair or fur.
Birds:
Have wings and feathers
Breathe air
Lay eggs
Cold-blooded:
Fish:
Have scales, fins and tails
Breathe underwater (using gills)
Reptiles:
Have dry skins and scales
Breathe air
Lay eggs
Amphibians:
Have smooth wet or slimy skins
Spend part of their life in water and part on land