The Animal Kingdom is the biggest of kingdom classifications because there are more animal species than any of the other kingdoms.
Even if you added up all of the organisms from the other kingdoms, the Animal Kingdom would be the largest.
In order to be a part of the Animal Kingdom, the organism must have three different characteristics.
The first characteristics is that they must rely on plants, or other animals to have nourishment.
The second characteristic is that they must be able to move around, and the third characteristic is that they have more than one cell.
Animals reproduce sexually meaning they have offspring that have the same genetic traits, and the offspring will look like their parents.
Animals have the ability to see, touch, taste, smell and hear. They are made up of millions of cells and the cells can divide and work together.
Animals have organ systems which help the animals to live.
Because there are so many different animals in the animal kingdom, they are divided into two different sections, vertebrates and invertebrates.
Vertebrates are animals that have backbones, and invertebrates are animals that have no backbone.
Vertebrates and invertebrates are then broken down to more groups, by putting them into groups such as reptiles, amphibians, birds, mammals and fish.