Animals are eukaryotic, multicellular organisms in the Kingdom Animalia. Animals comprise all multicellular organisms that have nervous systems. Most animals can move and react to stimuli, all vertibrate animals have a brain.
Almost all animals depend on photosynthetic Plants for the energy they need to live. Animals first appeared on Earth around 800 million years ago, and began to flourish during the Cambrian Explosion. The six types of animals are: invertebrates and five types of vertebrates, fish, amphibians, reptiles, birds, and mammals.