Navigation
Learning how plants and animals thrive in environments with very little water.
Imagine living in a place where it rains less than a small bucket of water in an entire year—how would you find a drink or stay cool without an air conditioner?
When you think of a desert, you might think of heat, but the real secret to a desert is dryness. A desert is any environment that receives less than inches ( cm) of precipitation per year. Because there are so few clouds, deserts can be very different. The Sahara in Africa is a hot desert where sand can reach . However, the Gobi in Asia is a cold desert. It is still incredibly dry, but it can be freezing cold and even have snow! Both types of deserts are harsh environments where every drop of water is precious.
Quick Check
True or False: A place must be hot to be considered a desert.
Answer
False. A desert is defined by how dry it is (low precipitation), not how hot it is.
Plants in the desert are masters of storage. A cactus doesn't have thin leaves like a maple tree because thin leaves lose water too fast. Instead, they have spines for protection and a thick, waxy skin that acts like a seal to keep moisture inside. Their stems are thick and fleshy to act as a storage tank. When it finally rains, a cactus can expand its body to hold as much water as possible, saving it for the many months of drought ahead.
The Saguaro cactus is a perfect example of desert engineering: 1. Spines: These protect the plant from thirsty animals looking for a drink. 2. Ribbed Stem: The stem has folds like an accordion that expand when it rains. 3. Shallow Roots: Its roots spread out wide just below the surface to grab rain before it evaporates.
Quick Check
Why do desert plants have waxy skin?
Answer
The waxy skin acts as a seal to prevent water from evaporating into the dry air.
How do animals stay cool when there is no shade? Many desert animals are nocturnal, meaning they sleep during the scorching day and come out at night when the temperature drops. Animals like the Fennec Fox have huge ears that help heat escape their bodies. Others, like the Gila Monster, spend most of their lives in underground burrows. These burrows act like natural basements, staying much cooler than the surface air. By staying underground or sleeping during the day, these animals save their energy and their body's water.
The Kangaroo Rat is a survival expert: 1. It never needs to drink liquid water; it gets all its moisture from the seeds it eats. 2. It stays in a deep, cool burrow during the day to avoid sweating. 3. It has specialized kidneys that waste almost no water when it goes to the bathroom.
Quick Check
What is the main benefit of being a nocturnal animal in the desert?
Answer
It allows the animal to avoid the extreme heat of the day, which helps them stay cool and save water.
Which of these is the defining characteristic of a desert?
How does a cactus protect its stored water from animals?
Nocturnal animals are active during the hottest part of the day.
Review Tomorrow
Tomorrow, try to explain to a friend why a desert can be both freezing cold and still be called a desert.
Practice Activity
Draw a picture of a desert animal and label two 'superpowers' (adaptations) it has to survive without much water.