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Image courtesy of Corel Photography
With over 2 million different kinds of animals, Kingdom Animalia is the largest of the
kingdoms. But when you think of an "animal", what image comes to mind? While
animals like bears, fish, and birds are the most familiar to us, over half of all the ani
mals on Earth belong to a group of animals known as "arthropods". Arthropods include
animals such as centipedes, crabs, insects, and spiders. This means that the majority
of animals come from a group of critters that give most folks the creeps!
So, what exactly is an "animal"? With so many different kinds of animals, it's hard to
imagine what they all might have in common. First, animals are "multicellular". This
means they are made of many cells, unlike bacteria, which are made of only one cell. Second, all animals must get their food by eating other
organisms, such as plants, fungi, and other animals. Plants don't have to eat other organisms because they can
use the Sun's energy to make
their own food. In addition, all animals need oxygen to survive. Did you know that fish
can breathe oxygen from the water that passes through their gills and earthworms get
their oxygen through their skin?
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