Extremophiles live in conditions outside the moderate environments that most life requires.
From high-temperature, deep sea vents to freezing, polar oceans, we’ll explore life in some of the most extreme environments on Earth.
What Are Extremophiles?
From tiny, single-celled organisms to complex creatures such as ourselves, most of the wondrous life on Earth thrives in moderate conditions. These are environments where it is ‘not too hot, not too cold, but just right,’ to take a line from the fairytale Goldilocks. Moderate conditions can also refer to salt content, or pH (a measure of how acidic or how basic an environment is). Most organisms require an environment that has a more neutral pH: ‘not too acidic, not too basic, but just right.
‘However, a whole class of organisms not only survives in extreme conditions, they thrive! Extremophiles (which loosely translates to ‘lovers of extremes’) are adapted to what is considered on Earth to be an extreme environment. From Antarctic ice to hydrothermal vents, extremophiles can be adapted to live in extreme cold, intense heat, harsh acidity, high saltiness, and a host of other conditions in which we humans have been surprised to detect life at all.
Types of Extremophiles
Extremophiles are adapted to their particular extreme environment; it’s not just that they can live there. To thrive, extremophiles must live in their special environment. For example, if a human put on a thick parka and spent some time in Antarctica, it wouldn’t make a human an extremophile. An extremophile is genetically adapted to its extreme environment. That means it’s unlikely to survive in moderate conditions.
Let’s look at some of the classifications of extremophiles. The key to the classification is in the name, which refers to the environment they are adapted to. Most extremophiles are microorganisms, but a few more complex extremophiles exist.
Thermophiles are heat-loving and are found in environments like deep sea vents, volcanic soil, and around geysers.Psychrophiles, also known as cryophiles, are just the opposite. These organisms are adapted to cold and live in places like polar seas.Halophiles thrive in high salt conditions. They live in brine and may be found in salt flats or lakes.
Acidophiles are adapted to extremely acidic conditions, such as volcanic landscapes.If an organism is adapted to multiple extreme conditions, it’s labeled a polyextremophile. For example, a thermoacidophile is adapted to hot (or thermo) and acidic (or acido) conditions.Now let’s meet some of these ‘extreme’ organisms!
Living in Acid
The microbe Picrophilus torridus, believe it or not, lives at pH 0, which is a very strong acid. If we humans got any liquid at pH 0 on our skin, it would cause a severe burn.
However, Picrophilus torridus, an archaebacteria, thrives in this environment. It was first discovered in northern Japan, in acidic fields that resulted from volcanic activity. Not only does this microbe live at an incredibly low pH, it survives at 65;C, and is therefore classed as a thermoacidophile.
Living in Antarctic Waters
The Antarctic krill is an extremophile that lives in the Antarctic Ocean. This psychrophile, or cryophile, is less than seven centimeters long, but can mass together with fellow krill to form large groups of over 10,000 organisms that can actually change water currents! The Antarctic krill helps bring carbon from the atmosphere into the ocean. It is one of the most abundant species in Antarctic waters, and as it provides nutrients for many polar species, it is a crucial member of the food chain. Since the krill must live in extreme cold conditions, the impact of rising ocean temperatures may be devastating for this species and the connected food chain.
Living in Heat
We’ve already seen one example of a thermophile (or heat-loving organism) in the microbe Picrophilus torridus.
A more complex thermophile living at high temperatures is found in deep-sea hydrothermal vents: the Pompeii worm. Though it has genetic adaptations that allow it to thrive in high heat, it also has a little help from bacteria. The Pompeii worm is covered in a sheath of bacteria that protect it from the extremely high temperature (it has been found in water temperatures up to 80°C). The bacteria acts like a protective suit in harsh conditions.
Again, extremophiles are adapted to conditions that are outside the moderate conditions most organisms on Earth require. Thermophiles thrive in extreme heat, psychrophiles (or cryophiles) are adapted to freezing temperatures, acidophiles live in highly acidic conditions, and halophiles survive in high salt environments.
Three examples of extremophiles are Picrophilus torridus (a thermoacidophile adapted to hot, acidic conditions), Antarctic krill (a psychrophile), and the Pompeii worm (a thermophile).