It’s true, there are more insects than there are any other specie and more kinds
The precambrian era makes up about 90% of the earths history, but there was little to no living organisms at the time other than microscopic ones. The first eukaryotes were found in the cambrian period after the precambrian period, not only that but at the end of the precambrian era in the Proterozoic era there was a mass extinction of about 70-80% of all living organisms
The system that is responsible for breaking down food and releasing essential nutrients and other substances that the body needs and requires is the digestive system.