All species are embedded in complex networks of interactions. ~ English ecologist Michael Pocock
There are 2 primary drivers of evolution: tolerance to environmental conditions and the ability to procure metabolic energy. Adaptation to the environment is expressed in myriad ways; likewise, energy procurement.
For those that can’t live off water and sunshine, meeting trophic needs is multifaceted, but boils down to what’s around to put on the menu. Animals adapt to consume others.