When you classify an animal you place it in the group to
which it belongs. All animals are divided into groups. The major groups are
fairly simple. Each group is then divided into smaller groups, and divided
again, until you eventually place the animal in its exact position in the
classification of the Animal Kingdom.
All of this may seem a bit complicated, and you are
right, it is. For now, we are going to study seven groups, divided between
animals with and without bones. We will only deal with insects
and spiders in the group with no bones, and mammals,
fish, birds, reptiles and amphibians in the group with bones.
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.
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.
There are five main groups. These groups can be split
further, into warm-blooded and cold-blooded 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.
Have hair or fur
Feed their young milk
Whiskers are a type of hair, so just having whiskers counts as having hair or fur.
Have wings and feathers
Have scales, fins and tails
Breathe underwater (using gills)
Have dry skins and scales
Have smooth wet or slimy skins
Spend part of their life in water and part on land