The animals volume increases as a cube of its radius, but its surface area only increases as the square of the radius. So as it gets bigger, more and more volume is covered by less and less surface area. They rely on a network of tubes that runs throughout the body of the organism, a vascular system. These closed tubes can circulate water and nutrients, and carry off wastes. Kingdom Animalia Kingdom Animalia includes 35 phyla and over 1 million species.
Animals are diploid, eukaryotic and multicellular.
All animals are heterotrophic. And all animals respond to external stimuli. All animals are motile, moving about at some point in their life cycle. Only animals can fly. J.B.S. Haldane once called animals wanderers in search of spare parts.