Camels live in extreme environments. A camel's two humps help it to store fat for energy in a barren, desert climate. The desert is one example of an extreme environment, or habitats where most living things, including humans, cannot thrive or survive. Sometimes, these harsh areas might have extreme temperatures. Others might have extremely high pressures or high amounts of acidity.

For quite some time, experts believed that extreme environments could not support life. Although most organisms cannot live in these extreme places, some life-forms—known as extremophiles—have adapted to such conditions.

An environment is extremely acidic when conditions are less than 5 on the pH scale. In chemistry, pH is a scale used to determine how acidic or basic (alkaline) something is. It ranges from 1 to 14. A level of 1 is extremely acidic and a level of 14 is extremely basic. A level of 7 is neutral. The optimal pH level for a human is around 7.35 to 7.45, so it is slightly basic.

Extremely Acidic Habitats

Extremely acidic habitats are found around the world. Volcanic and geothermal areas, such as hot springs, have large amounts of sulfuric acid. The acid produces particularly low pH ecosystems. Some examples of extremely acidic environments include the red-tinted Rio Tinto river in Spain and geysers in Yellowstone National Park in the United States.

Acidophiles are creatures that can live in acidic environments with pH levels between 1 to 5. One acidophile is Cyanidium caldarium, a type of red algae. For most animals, high acid levels destroy or damage their cells. This is not the case for acidophiles. They have evolved ways to preserve their cells' internal pH levels at around 7. Acidophiles can possibly provide some answers to many human needs, including their potential use for bioremediation. This is a process where microorganisms are purposely introduced into the environment to break down a toxic contaminant.

Basic Environments and Temperatures

The opposite of acidic environments is basic, or alkaline, environments. They feature natural habitats above a pH level of 9. They are also found around the globe in areas with high geothermic or volcanic activity. Yellowstone National Park's hot springs and the Great Rift Valley in northeastern Africa host extremely basic environments.

Bitter cold, dry environments are extreme habitats, which continuously reach temperatures below 5 degrees Celsius (41 degrees Fahrenheit). They include environments like those found in polar regions. Studies have discovered that some microbes survive and live well in various cold regions. In 2013, a team of scientists discovered bacteria under the ice in Antarctica. These bacteria are a type of psychrophile, meaning they are microorganisms that grow best at temperatures of 15 degrees Celsius (55 degrees Fahrenheit) and below.

Some of the most extreme habitats boast temperatures of more than 40 degrees Celsius (104 degrees Fahrenheit). This is too hot for many living things to handle. These sites include deep-sea vents and hot springs. Thomas Brock, an American microbiologist, discovered microorganisms surviving in Yellowstone's scalding hot springs in 1966. The organisms that live best in extremely high temperatures are called thermophiles. They have been found all over the world in hot springs and geysers.

Deserts are also considered to be extreme, hot environments where some animals, such as the sidewinder snake, have learned to survive there. They have developed an effective way to slither across the hot sand where they do not move lengthwise, like most snakes. Instead, they move their bodies so that only parts of it touch the hot sand at once. This limits the amount of body exposed to the burning sand.

What Can We Learn from Extreme Environments on Earth?

The living things that have learned to thrive in such harsh habitats can provide answers to important questions. Take Alaska's wood frogs (Lithobates sylvaticus), for example. These amphibians freeze when winter arrives in the far northwestern U.S. state of Alaska. When spring appears many months later, the frogs thaw and continue on with their lives.

How can this be? Scientists have discovered that the frogs produce chemicals that prevent ice crystals from forming. Ice crystals would normally pierce the frogs' cells and organs. By studying this species and its unique adaptation, scientists hope to discover a way to successfully store human organs. The goal is to store organs for an extended amount of time to save them for future transplantations. Currently, organs cannot last longer than a few hours when refrigerated; they are destroyed when frozen.

The tiny tardigrade, also known as the water bear, can survive in many different kinds of extreme environments. This includes the high altitudes of the Himalaya, the intense pressure of the deep ocean, the frigid temperatures of Antarctica, and a 10-day journey to space. This microscopic organism could potentially help us learn more about what kinds of organisms that could live on planets with extreme environments like Mars.