No one knows exactly how many types of animal there are. So far, scientists have made a list of 1.5million species, but many think the total number could be nearer to 30 million. The great diversity of life – or biodiversity – came about through evolution over billions of years. Animals now survive almost everywhere on Earth, from the depths of the ocean floor to the hot desert sands. Such great variety makes the natural world fragile, since it is all too easy for unusual animals to become endangered. At the same time, biodiversity makes wildlife resilient. Evolution thrives on variation, and so animal life will always be able to adapt to whatever nature throws at it.
Biodiversity helps keep each ecosystem, and our whole world, in balance; so if one species goes extinct, another is there to take its place.
Species loss threatens to reduce biodiversity, the presence of a variety of species in a given area, which is key to sustaining both local ecosystems and the global ecosystem more broadly. Biodiversity helps ensure that certain specific and necessary functions are carried out within an ecosystem — think about how pollination allows plants to flower and predators eliminate pests. Biodiversity ensures that if one species goes extinct or leaves a particular region, another is there to take its place. Ultimately, the collapse of ecosystems can lead to even bigger problems like the worsening of climate change, because of the increased release of carbon dioxide.
Many species also play key cultural and economic roles that if lost would threaten local communities. Endangered bees play a key role in pollination for agriculture. Coral reefs play a key role maintaining coastal fisheries. African elephants attract tourists to sub-saharan Africa.