The Biosphere: Life on Earth

Earth’s biosphere is the layer of the planet where life exists.

That means you, me, plants, insects, bacteria, and living things on land, air, and oceans make up the biosphere.

And in case you were wondering… viruses are part of the biosphere too. But they can be a bit tricky.

Today, let’s explore Earth’s biosphere. One of Earth’s spheres that is completely unique to our planet.

What are examples of the biosphere?

Organisms in the biosphere rely on each other as part of the food chain. The food chain is the building block of the biosphere where energy is transferred from one level to the next.

PRIMARY PRODUCERS: Plant life and ocean phytoplankton (tiny plant-like organisms in the oceans) are examples of primary producers. These organisms are at the bottom of the food chain and power the entire biosphere.
HERBIVORES: Herbivores feed on plants. Then, predators consume herbivores. Humans and apex predators are considered to be at the top of the food chain.
DECOMPOSERS: Finally, decomposers break down matter so they can be recycled as part of the nutrient cycle. This completes the full circle because all matter becomes part of the food chain once again.

What diagram illustrates the biosphere?

The biosphere is all closely tied together as a collection of different parts. The biosphere (living organisms) interacts with:

The hydrosphere (liquid water)
Lithosphere (solid rocks)
Cryosphere (frozen ice)
Atmosphere (gas envelope)

For example, living things inhale oxygen and exhale carbon dioxide (CO₂) from the atmosphere. Then, plants pull CO₂ during photosynthesis to build their structure (mostly glucose).

The biosphere constantly interacts with Earth’s spheres. For example, living things pull water from the soil and air. And oceans soak up carbon from the air. Finally, specific bacteria from the biosphere are only capable of building certain types of rocks.

Where is the biosphere on Earth?

“You can find life almost anywhere on Earth. Where there’s life, the biosphere is present. Even in the most extreme circumstances, life can persist.”

For example, polar regions, ocean vents, and the deep biosphere are extreme environments in their own unique way. But they can all harbor life.

Polar Regions

Plants and animals in polar climates endure frigid temperatures year-round.

For example, Antarctica is the world’s largest desert averaging −10°C to −60°C. In these polar regions, the biosphere mostly consists of algae, lichens, and mosses.

Animals exist too. For example, penguins eat krill, a fish common in the Southern Ocean. They also have a thick layer of skin and feathers (for waterproofing) for surviving the frigid temperature.

Hydrothermal vents

Deep beneath the ocean, the Earth cracks open. Iron-rich sulfur, carbon dioxide, and minerals spew out at these underwater volcanoes.

But what’s surprising is how hundreds of species of animals can still flourish. They don’t need light to survive. Instead, they rely on a process called chemosynthesis [1].

Even more interesting is that these underwater vents are possibly the origin of the Last Universal Common Ancestor (LUCA).

Deep biosphere

The deep biosphere extends deep into the Earth’s crust. Similar to hydrothermal vents, microorganisms can thrive.

For example, bacteria were found in the crevices of rocks at 500 meters in depth [2]. As deep as 3 kilometers, bacteria exist in anaerobic, hot, and high-pressure environments.

90% of Earth’s carbon resides inside Earth [3] which is the chemical backbone for all essential organic molecules produced by living organisms.

How old is the biosphere?

The biosphere is unique to Earth because it’s the only planet known to support life.

It’s believed that Earth’s biosphere started about 3.5 to 4.1 billion years ago. All living things originated from a common ancestor called the last universal common ancestor (LUCA).

Archaea are believed to be the oldest domain of life. They make up a group of the first organisms to appear on Earth. We know this because they are used to extreme environments like those during the early Earth.

Archaea resembles both eukarya and bacteria. They are single-cell without a nucleus. But they look like bacteria for structure.

Since the evolution of our very early ancestors, the biosphere has altered land, air, and water for over a billion years.

How much does the biosphere change?

The biosphere is constantly in flux. It fluctuates in the short term based on the seasons. And it changes in the long-term from climate change.

Net primary productivity is unique to the biosphere. It’s the rate at which plants take in carbon dioxide during photosynthesis minus respiration.

Productivity peaks in the summer for mid-latitude regions. But when winter comes, productivity drops because of the lower rate of photosynthesis.

Tropical rainforests are the most productive places on the planet. Whereas, polar regions are the least productive ecosystems.

The Biosphere: Life on Earth

The biosphere is the sphere of life on earth. It consists of all the living organisms, their habitats and biomes, and associated non-living components that interact with them, forming a single interdependent system.

Do you want to learn more about the biosphere or biology in general? If you do, check out some of the courses below to advance your career in biology:

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