There are a lot of types of creatures figuring and fighting out their ecosystems.

And the land we say is just the surface of the Earth. There are insects, ameba, bacteria they may not be birds or mammals but they are also part of like and ecosystem and it boils down to everyone contributing to the cycle.

This may not be the answer but something to ponder upon as it helps you to visualize life.

Bees and vultures are so so cool as well