Animals are members of Kingdom Animalia, also known as Metazoa.
All animals are multicellular and motile, meaning they can move impulsively and independently.
For all they have in common, different animal species vary in spectacular ways. Some are more active at night (known as nocturnal) while others are most active during the day (known as diurnal). Some are merely a few cells; whiles others can weigh several tonnes.
The five most well-known classes of fauna are:
Mammals (such as lions and monkeys)
Birds (such as ducks and emus)
Fish (such as sharks and snapper)
Reptiles (such as snakes and crocodiles) and
Amphibians (such as frogs and salamanders).
The exact number of animal species existing on Earth is still not known, with around 17-18,000 new species being discovered every year.