All living animal comes from one cell but we became multicellular organisms of different shapes and sizes. Although we have become complex creatures, our cells are able to do this because they are able to copy themselves, divide, and transform continuously so as to be able to build complex bodies which could be tissues, organs, and then become system. This cells can range from millions in Ants to hundreds of trillions in larger animals like whales and for we humans, we are made up off about 37 trillion cells.