Surface area to volume ratio is a measure of the amount of surface area (like skin or a membrane on a cell) relative to the volume of the object. This concept is pervasive in science and there are numerous examples of it. As an object gets smaller (or as it gets broken into smaller and smaller pieces) the object increases the amount of surface area relative to the volume of the object. This is why granulated sugar dissolves much faster than the same volume of sugar cubes. The granulated sugar has much more surface area.
Examples in nature:
-This is the main function of chewing food, we mechanically break it into smaller pieces to increase the surface area to make digestion more efficient.
-This is why your fingers are the first parts of your body to get cold, they are smaller and have a higher SA:V Ratio. Since body heat is produced by the volume of your body and lost by the surface area of your skin, a higher SA:V ratio causes your body to lose heat faster than other areas. This premise is also why whales are such gargantuan creatures. They live in frigid cold temperatures and the size helps them keep much of their body heat. It is also the reason elephants have huge ears. The massive surface area of the ear helps the elephant cool down when it gets too hot in the African sun.