Explain why species found in cold habitats tend to be larger than related species found in hot habitats

Question

What will be an ideal response?

Answer 1

A key factor in heat balance is an animal's surface-area-to-volume ratio. The heat an animal generates is proportional to its volume. The heat an animal loses is proportional to its surface area, since heat is lost to the environment through its body surface. Consequently, animals are better able to lose heat if they have a high surface-area-to-volume ratio, and better able to retain heat if they are have a low surface-area-to-volume ratio. Larger organisms tend to have smaller surface area-to-volume ratios. This is because volume increases more quickly than surface area as organisms get bigger. For this reason, animals found in cold habitats are often larger than related forms in warm habitats—it helps them retain heat.