Natural selection is a type of evolution that allows organisms to adapt into the environment they're in for survival.
These chemical processes require energy. The respiration and metabolism require adenosine triphosphate (ATP) which is cellular energy, and the organs get their fuel from the calories we consume. Without this energy, we eventually die
1kdkdmdmfmfdhxhsususjsbsbsbdbdndnsjzjjzjxnxjxjxjxjjxjdudjxidjdjdjdjdjdjdjdndj
Invertebrate doesn't posses "Backbone" whereas Vertebrate chordate have that. That's the only & most important difference between them.
Hope this helps!