Here you see an example of diversity among fungi from just one part of Canada. |
Life on Planet Earth
We currently know of 2 million different types of organisms on Earth, each with its own unique set of traits. New ones are discovered almost every week, and by the time they are all discovered, there may be as many as 10 million on Earth. In addition to these, millions more have lived here in the past but are now extinct. The great variation of life forms on Earth is called Earth’s biodiversity.
As far as we know, Earth is the only planet that supports life. Here are a few important facts about Earth and why it is uniquely suited for supporting such a rich diversity of life:
- Earth is the only planet that has sufficient oxygen, which is a gas needed by all animals including humans.
- Earth supports photosynthesis, the reaction whereby plants take carbon dioxide from the atmosphere and use sunlight to make their own food. In doing so, they give off oxygen as a byproduct, thus contributing to Earth’s oxygen-rich atmosphere.
- Earth is the only planet that has water in all three phases: solid, liquid, gas. It is the only planet that has sufficient liquid water to support living things.
- Earth has an ozone layer, which is a layer of gas in the upper atmosphere that protects Earth from harmful solar radiation.
- Earth has the right temperatures to make liquid water possible and to support a wide range of environments and living things.
- Because of Earth’s spin on its axis, all sides of Earth receive sufficient sunlight every 24 hours.
