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The Desert
General characteristics
Deserts cover about one fifth (20 percent) of the earth's land area. The desert is very dry and often hot. The
desert is a harsh environment with very little rainfall and extreme temperatures; a desert is defined as a
region that gets less than ten inches of precipitation per year. Some deserts get both very hot (during the day)
and very cold (during the night, when temperatures can drop well below freezing). Some deserts, however,
are always cold. Most Hot and Dry Deserts are near the Tropic of Cancer or the Tropic of Capricorn (between
30 degrees latitude north and 30 degrees latitude south). Cold Deserts are near the Arctic part of the world.
There is a lot of direct sunlight shining on the plants. The soil is often sandy or rocky and unable to hold much
water. Winds are often strong, and dry out plants. Plants are exposed to extreme temperatures and drought
conditions. Plants must cope with extensive water loss. Because of these dry conditions, there is limited plant
and animal life in deserts.
The Desert
Plant Adaptations
Desert plants have two main adaptations:
Ability to collect and store water
Features that reduce water loss
Plant Adaptations include the following:
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Some plants, called succulents, store water in their stems or leaves;
Spines or thorns to discourage animals from eating plants for water;
Long root systems spread out wide to absorb water;
Waxy coating on stems and leaves act like a plastic wrapper to help reduce water loss;
Many plants have no leaves. The lack of leaves helps reduce water loss during photosynthesis. Leafless
plants conduct photosynthesis in their green stems;
Some plants have a short life cycle, germinating in response to rain, growing, flowering, and dying
within one year. These plants can evade drought;
Leaves with hair help shade the plant, reducing water loss. Other plants have leaves that turn
throughout the day to expose a minimum surface area to the heat;
Flowers that open at night lure pollinators who are more likely to be active during the cooler night;
Slower growing requires less energy. The plants don't have to make as much food and therefore do not
lose as much water.
This cactus displays several desert
adaptations: it has spines rather
than leaves and it stores water in
its stem.
This cactus displays light-colored
hair that helps shade the plant.
This plant has a waxy coating
on its leaves.
The Desert
Animal Adaptations
Different animals live in the different types of deserts. Animals that live in the hostile desert environment have many
adaptations to cope with the lack of water, the extreme temperatures, the searing sun and the shortage of food.
To avoid daytime heat, many desert animals are nocturnal(only active at night); they burrow and sleep beneath the
surface or hide in the shade during the day, coming out at night to hunt and eat. A small agile snake, the sidewinder
takes refuge in the burrow of another animal or under a bush during the day. At night it emerges to hunt its
prey, mainly small rodents, such as pocket mice and kangaroo rats, and lizards. Some animals rarely spend any
time above ground. Spadefoot toads spend nine months of every year underground!
Some animals store food in their bodies as fat when food is plentiful. The fat sand rat overcomes the problem of
the unpredictability of desert food supplies by laying down a thick layer of fat all over its body when food is
abundant. It then lives off this fat when food is short. The Gila monster, a heavy-bodied lizard has a short,
usually stout tail, in which it can store fat for use in periods of food shortage.
Many desert animals do not have to drink at all; they get all the water they need from their food. Most desert
animals are small carnivores. There are also insects, arachnids, reptiles, and birds.
Gila Monster
Sidewinder
Fat Sand Rat
Roadrunner