Animals are an essential component of our world. It plays an important role in balancing ecosystem or biodiversity. There are a huge number of animal species. It is expected that our planet Earth has about 8.7 million animals species. But due to extinction problem, we have only 1.2 million species in existence. Every classification of living organisms belongs to one Kingdom, of which there are five in total. These Kingdoms are known as Animals, Plants, Fungi, Protista, and Monera.
