Adaptations: Deserts

Here we are in a large, dry area of land. There are hardly any plants growing here. It is a desert. Most experts agree that a desert is an area that receives less than 25 centimetres of rain and snow per year. In deserts, the amount of water vapour in the air — the humidity — is usually near zero.

This lack of humidity affects the temperature. During the day, heat from the sun reaches the air and the temperature climbs — to an average of 38°C in hot deserts. Some of this heat is absorbed by the ground, then radiated back into the air. But the lack of humidity in the air means the air cannot hold the heat. When the sun sets, the temperature drops a lot – down to an average of -3.9°C.

Brr! These are tough conditions, but many plants and animals have adapted to cope with the lack of water and extreme temperatures in deserts. Take this cactus. See its thin, pointy spines? These are its leaves.

Their very small surface area reduces the loss of water through transpiration. This is great for retaining water but... what about making food? In most plants, the process of making food, called photosynthesis, is carried out by the leaves. Since desert plants usually have very small leaves, most carry out photosynthesis using their green stems.

The stems of many desert plants, such as cacti, are covered with a thick waxy layer called cuticle which also prevents water loss. If we look underground, we can see that the roots of desert plants are also well adapted. The prickly pear cactus, for example, has very thin roots that remain near the surface and spread out across many metres. These help the cactus collect water quickly if it rains. The mesquite tree, however, has long, deep roots.

These are called taproots, and they help the tree absorb moisture and nutrients from deep underground. And here comes a hungry camel! How have animals like him adapted to desert conditions? The camel’s long eyelashes have a special function, as do its hairy ears and closable nostrils: to help keep out blowing sand. Its wide feet, meanwhile, prevent it from sinking into the sand.

On its back, the camel has bulges called humps. These humps allow camels to survive without drinking water for more than a week! How? Are they filled with water? No, not with water, but with fat.

When food and water become scarce, the camel gets energy from this fat. As it is used, the humps go down. They deflate. And when camels do find a drink, they can rehydrate faster than any other mammal. Camels can drink 100 litres of water in a matter of minutes!

It's not just physical adaptations that help desert animals survive. They also modify their behaviour. This meerkat, like many small desert animals, shelters by burrowing into the ground where the temperature is several degrees lower. And this fennec fox, found in North African deserts, makes sure to hunt at night when temperatures are cool. This way, it avoids the extreme daytime heat.

Animals that use this adaptation are described as nocturnal. It is not easy to live in the desert, but some plants and animals are up to the challenge, thanks to their structural, physical, and behavioural adaptations.