The main purpose is communication. like when you stub your toe , your nervous system communicates to your brain to react and have pain
Answer:
All animals share a common ancestor.
Explanation:
All living organisms including animals have evolved from common ancestral organism. It is evident from various researches in relation evolutionary diversification of species. The process by which numerous variety of species are formed from a common ancestor is known as speciation. The attached diagram showing the phylogeny tree of life is a solid evidence of common ancestral origin of life.
Fat; they store twice as much energy per gram
That would be the sun. Hope this helps.