The Four Spheres of the Earth for Kids

Studying the planet as a whole is complicated. To do this, it is divided into terrestrial spheres. The spheres are four: Hydrosphere, Geosphere, Biosphere and Atmosphere.

The Earth as a System

The planet Earth functions as a large system composed of four spheres or main terrestrial subsystems that are related to each other. This means that they depend on each other and influence each other.

The Earth as a System
The 4 Spheres of the Earth for Children

What are the four Terrestrial Spheres?

Studying the planet as a whole is complicated. To do this, it is divided into terrestrial spheres. The spheres are four: Hydrosphere, Geosphere, Biosphere and Atmosphere. The slightest change in one of them affects the rest. They maintain a relationship of constant exchange. Human beings have a responsibility to maintain that balance.

1. Biosphere

The biosphere contains all living beings and organisms on the planet. This includes microorganisms, animals and plants. It is separated into ecological communities according to the area in which they live. These communities are called terrestrial biomes. They are large areas characterized by their vegetation, soil, climate, and wildlife. The different terrestrial biomes are usually defined by their vegetation, such as trees, shrubs, and grasses.

Types of Terrestrial Biomes

There are different main types of biomes: Tundra, boreal forest, temperate forest, tropical forest, grassland, chaparral, desert. Some of these biomes can be divided into more specific categories such as marine water, fresh water, savannah, temperate rainforest, and taiga. Factors such as latitude, humidity and altitude affect the type of biome.

The biosphere interacts with the other spheres of our planet exchanging matter and energy. It contributes to the development of cycles such as those of nitrogen, phosphorus, carbon, sulfur and other elements.

Types of Terrestrial Biomes
Types of Terrestrial Biomes for kids

Primary Producers and Biosphere

The biosphere is dynamic, which is why it affects the so-called primary producers, who are the ones who make their own food from photosynthesis.

The seasons of the year are determined by the irradiation of the sun’s rays in the terrestrial hemispheres and have a determining effect on photosynthesis. The production of energy generated by photosynthesis decreases sharply during the winter months. Both photosynthesis and nitrogen fixation are critical to the functioning of terrestrial systems as a whole.

What is a Food Chain?

They are the feeding relationships between producer, consumer, and decomposer organisms. Living beings feed on each other establishing the food chain.

For matter and energy to flow within an ecosystem, there must be a balance in the links of the food chain.

 One is “eaten” by the other. Food is passed from one living thing to another in repeated “eating and being eaten” activities. Based on this, the links of this chain are established.

Levels of the Food Chain

Primary Producers

Primary producers are a fundamental part of an ecosystem and the first step in the so-called food chain.

Living things that are autotrophs are called producers. They occupy the first link in the food chain. They are green plants that with sunlight make their own food through photosynthesis.


They are called consumers because they obtain their food by consuming other living things. However, not everyone eats the same.

1. First-order consumers are heterotrophic herbivorous animals that consume biomaterials from other organisms. They take their energy and nutrients by consuming the producers. They feed on plants to be able to live, leaves, stems, flowers, fruits, roots or even seeds. For example they are mice, vicuñas, deer, fish, birds, bees.

2. Second-order consumers are carnivores that eat herbivorous animals and thus obtain energy. For example, they are the sea lions, the puma, the fox, the boa.

3. Third-order consumers are carnivores that eat other carnivores.

Predatory animals

They are the ones that capture or hunt other animals in order to feed themselves.


They obtain food from the remains of organisms, from leaves, excrement from dead animals. They transform them into simple substances such as water and carbon dioxide, which can serve as food. For example, fungi and some microorganisms such as bacteria. They return materials to the soil and fertilize it. In this way, matter is recycled over and over again in nature.

The Four Spheres of the Earth Diagram for Kids
The Earth’s Spheres Diagram for Kids

Fun Facts about Nitrogen on our Planet

• Nitrogen is a fundamental component of the organisms of living beings. It is found in all proteins and in DNA.

• Nitrogen exists in the atmosphere in a gaseous state. During nitrogen fixation, bacteria convert it into ammonia, which can be used by plants. When animals eat plants they acquire these nitrogenous compounds and thus can use them.

• Human activity affects the nitrogen cycle. Due to the use and abuse of fertilizers containing nitrogen and phosphorus. When these reach rivers and lakes they can cause algal blooms, a process known as eutrophication.

• Nitrogen is a limiting nutrient. What does this mean? In natural ecosystems processes, such as primary production and decomposition, are limited by the amount of available nitrogen. This means that it is the nutrient that is found in the least amount and that it restricts the growth of organisms.

What Is Eutrophication? Eutrophication Process & Steps

It is the contamination of salt or fresh water due to an excessive supply of nutrients, especially nitrogen and phosphorus.

Eutrophication can reduce the availability of oxygen in the water at night. Algae and microorganisms that feed on algae use large amounts of oxygen in a process called cellular respiration. The excessive growth of algae in eutrophic waters is accompanied by the generation of a large amount of dead algae. These sink to the bottom of the water, where they are broken down by consuming bacteria, resulting in the formation of dead zones. They are areas incapable of supporting life, with little oxygen and without species.

2. Hydrosphere

The hydrosphere is the layer of water that surrounds the planet. It is defined as the set of liquid parts present on Earth. Water circulates continuously changing its physical state (solid, liquid, gaseous) in a cyclic succession of processes that constitute the so-called water cycle. It is the fundamental cause of the constant transformation of the earth’s surface, regulates the climate and makes life possible on the planet. The energy so that the changes of state of the water and the hydrological cycle can be carried out comes from the Sun.

The water of the hydrosphere is distributed irregularly on the planet: we find it in oceans, seas, lakes, rivers, glaciers (in a solid state), groundwater, water vapor in the atmosphere and it is an essential part of living organisms.💧​

Living beings contain a large proportion of water in their bodies. 97% of the water on planet Earth is salt water, only 3% is fresh. For this reason we must take care of it, not contaminate it, or waste it.

Read also: Characteristics and Classification of living Organisms

3. Geosphere

The Geosphere is essential for life on the Planet. In many places on our planet, the geosphere has a surface that provides living organisms with the essential nutrients for their survival. It is made up of three layers:

• Crust: It is the outer layer formed by the continents and the bottom of the oceans. It has two parts: an external one (composed of silicon and aluminum) and an internal one (composed of silicon and magnesium).

• Mantle: It is located below the crust and is composed of silicates, iron and magnesium.

• Core: It is the deepest part of the Earth where it is so hot that the rocks have melted.

Also read: Earth and Space for kids

4. The Atmosphere

What are the four Terrestrial Spheres?
What are the four Terrestrial Spheres?

The atmosphere is a gaseous layer that surrounds the Earth and is held together by the force of gravity. This gas envelope is not uniform. At its widest it is about 1.000 kilometers thick. It is essential for life.

The gases that make up the atmosphere are oxygen, nitrogen, helium, carbon dioxide.

Layers of the Atmosphere and their Functions

• The atmosphere acts as a filter for harmful radiation. If these radiations reached the Earth, they would cause significant damage to living beings.

• It is a “shield” for meteorites. Meteorites are rocky bodies that come from space that disintegrate when they collide with the air. The air in the atmosphere manages to slow them down because it applies resistance.

• Provides the gases that living things need to breathe.

Regulates the planet’s temperature by determining the weather and climate.

As we move away from the Earth’s surface, the atmosphere presents different characteristics depending on the composition of the gases and the temperature.

Layers of the Atmosphere

In order to study the atmosphere we divide it into five (5) different layers:

The major layers of the atmosphere are:




• Thermosphere


Read more here: Layers of the Atmosphere easy for kids

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