* Biosphere: This is the most obvious one! Animals are a major component of the biosphere, which encompasses all living things and their environments.
* Hydrosphere: Animals live in all types of water, from oceans to lakes to rivers. Think of fish, whales, dolphins, and even some insects!
* Atmosphere: While some animals are only found in the atmosphere briefly (like birds migrating), some insects actually spend their entire lives in the air, like some types of flies.
* Geosphere: Animals can be found in various parts of the geosphere, like in caves or underground burrows. Some species even live in extreme environments like deep ocean trenches.
So, the answer is all of the Earth's systems!
