"Natural Science 4" is an interactive encyclopedia that includes scientific information in the understanding of fourth grade students, wonderfully illustrated and animated.
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* Chapter 2 Lesson 10 *
* The Desert *
The desert is among the most inhospitable places on Earth. Here, rainfall is low or even non-existent, and temperatures are extremely high. Some deserts are hot all year round, with temperatures sometimes exceeding 50 degrees Celsius (for example the Sahara). Others are cold, barren and rocky, with small patches of bush (to illustrate the Gobi Desert). Only very hardy plants can live here. Since plants need water, a rarity in these places, they need to keep it as long as possible.
One of the most resistant plants is the cactus. Its thick and succulent stem, smooth and seemingly waxy, thorn-shaped leaves help reduce water loss. It takes in the carbon dioxide needed for photosynthesis only in the cool of the night.
Other desert plants, such as mesquito bushes, store water in their underground root system, away from the heat of the sun. California poppies are plants that bloom only when precipitation falls.
Although the landscape seems desolate, a wide variety of animals live here.
The biggest problems facing the animals here are lack of water and intense heat.
Small mammals like kangaroo rats and ground squirrels spend their days underground, protected from the sun's scorching rays. They come to the surface in search of food only at night. Reptiles need the warmth of the sun to become active. That's why they go hunting in the morning or in the evening, when it's cooler, and during the day they stay hidden in burrows or in the crevices of the rocks. Some beetles spend the night with their heads in the sand. Thus, water droplets form on their backs as a result of condensation. These flow to the mouth and are swallowed.
Some large mammals, for example the camel, dromedary and mendes antelope, have thicker fur on their backs (to protect them from the sun) and thinner fur on their abdomens to remove excess body heat. They can conserve water in their bodies, needing only a small amount to live. They have wide feet that give them stability on the sand, long eyelashes and nostrils that can close to protect their eyes and nose from the sand. Some carnivores use the water from the food they eat. Birds fly long distances in search of the precious liquor.
Scorpions, the desert tortoise, the meerkat, the rattlesnake and the fennel, i.e. the desert fox, are also adapted to this environment.
Life is not more comfortable in the cold deserts either. For example, the Gobi Desert in Mongolia is buffeted by intense winds. Here, temperatures can drop to minus 40 degrees Celsius in winter.
The coldest and driest desert is in Antarctica, where it is cold all year round. Vegetation is almost absent. The emperor penguin and cormorant have a thick layer of fat and feathers to protect them from the cold and wind.
How do you think man adapts to this living environment?