Biology Revision Cards

The surface area to volume ratio is very important when you look at the adaptations of animals that live in cold climates. The smaller the surface area to volume ratio the easier it is to reduce the transfer of energyto the environment and minimise cooling. Animals in very cold climates often have other adaptations too. The surface area of the thin-skinned area of their bodies, such as their ears, is often small, reducing cooling through energy transfers to the environment. Many mammals in cold environments have plenty of insulation. Inside they have blubber, a thich layer of fat that builds up under the skin. On the outside they have a thick fur coat.

Camouflage is a form of of structural adaptation that is important to both the predators (so their prey doesn't see them) and the prey (so they can't be seen). Many arctic animals, for example the arctic fox, have grey or brown summer coats that change to pure white in the winter. The colour coat of a lioness is another example of effective camouflage. The sandy brown colour matches with the dried grasses of the African savannah.

Dry climates are also hot climates- like deserts. Many desert animals have functional adaptations in their kidneys so they can produce very concentrated urine and need little or nothing to drink. They get water from the food they eat. Animals that live in hot conditions often adapt their behaviour to keep cool. They are often most active in the early morning and evening, when it's cooler. During the cold times and hottest times of the day, they rest in burrows or shady areas. Many desert animals are relatively small with large surface area to volume ratios. They often have large thin ears to help them transfer energy to the surroundings through their skin, cooling them down.

Study tip-

Remember that animals living in very cold conditions often have a low surface area to volume ratio. This means there is less area for energy transfers to the surroundings and so less cooling. The opposite is true in hot climates.

Key points-

Organisms, including animals, have features (adaptations) that enable them to survive in the conditions in which they normally live. These adaptations may be structural, behavioural or functional.