Effect of temperature, water, light, and soil on habitat selection.
This article offers an overview of major abiotic factors that influence habitat, including temperature, water, light, and soil.
Key terms
| Term | Meaning |
|---|---|
| biotic factors | living components that influence an organism's habitat |
| abiotic factors | non-living, physical or chemical components that influence an organism's habitat |
| eurythermal organism | organism that can tolerate a wide range of temperatures |
| stenothermal organism | organism that can only tolerate a narrow range of temperatures |
| euryhaline organism | organism that can tolerate a wide range of salinity |
| stenohaline organism | organism that can only tolerate a narrow range of salinity |
How do organisms choose their habitat?
If you could live anywhere in the world, where would it be? Inside a volcano? Underwater? In a cosy house in the city?
Realistically speaking, we take practical considerations into account for making this decision, like the neighborhood, the weather in that region, the availability of nearby shops, and so on.
If we were to zoom out and look at how all organisms (not just humans) choose their habitats, we can broadly classify these influencing factors into living (biotic) and non-living (abiotic) components. For example, the survival of a species of fish in the ocean might depend on the type of predators present, the pH of the water, the kind of competition it has for food, and so on.
Try and classify them based on whether they’re living or non-living - so the predators and competition will be biotic factors, while pH will be abiotic.
Together, these factors decide what range of conditions an organism can survive within.
Let’s take a closer look at some of the major physico-chemical, or abiotic, factors that influence habitat.
Temperature
There is an incredible range of temperatures on our planet, from very hot (around the equator), to very cold (at the poles, high altitudes or deep underwater), and including everything in between. Metabolism is the machinery that keeps organisms alive - and since this machinery is very temperature-sensitive
You might remember that all living cells have enzymes and chemical reactions that take place within them. All metabolic reactions have optimum temperatures, outside of which they slow down or do not take place at all.
On top of that, enzymes and proteins can get denatured outside their optimum temperatures, which will bring the metabolic machinery to a grinding halt, causing all kinds of problems!
, there is a clear reason for life forms being distributed within their optimum temperature ranges.
That being said, there are always exceptions to the rule. While most living beings can only survive in a narrow range of temperatures (stenothermal organisms), some have wide thermal ranges across which they can function (eurythermal organisms).
Extremophiles are organisms that can live under (as the name suggests) extreme conditions. For example, thermophiles thrive in regions with extremely high temperatures, like near or inside hydrothermal vents. There are all kinds of bacteria, plants, and worms that flourish near boiling temperatures in these places.
On the other hand, psychrophiles or cryophiles live in regions with very low temperatures. These organisms are also often bacteria, insects, or other invertebrates like frogs. One lichen (the sunburst lichen) is known to photosynthesize at
Water
You've probably heard about or seen news articles about the hunt for water on other planets. This is because life is tied directly to the presence and quality of water. In arid regions, organisms adapt to survive with limited water resources.
Aquatic organisms obviously need water, but they also need specific types of water. pH and salinity determine the distribution of some organisms. Similar to temperature, organisms can either tolerate very small ranges of salinity (stenohaline), or wide ranges (euryhaline).
test your understanding 1
Tardigrades are tiny,
Which of the following statements best describe the nature of such tardigrades?
Light
As you might have guessed, light is very important for the survival of most plants. Similar to organisms in the desert, plants that receive low illumination learn to photosynthesize optimally in such conditions. In some regions like deep underwater, where all of visible light does not penetrate, marine plants utilize only some wavelengths of light.
But it's not just plants that are affected by the presence or absence of light. Several behaviors of animals including feeding, sleeping, migration, and so on depend on the intensity and duration of light.
Visible light emitted by the sun includes blue light, which peaks during the day. However, our digital devices also emit blue light. Exposing ourselves to blue light at night sends confusing signals to our brains, that might mess up our circadian (sleep-wake) cycles.
This is why you might see a feature on your phone that tints the display a yellowish color at night, or even restricts screen time.
Soil
Several characteristics of soil influence life, including composition, grain size, nutrient content, pH, mineral composition, and water holding capacity.
Apart from these
test your understanding 2
A species of bacteria are evolving to spread across a region.
Which of the following are examples of abiotic factors that might affect its distribution?
test your understanding 3
A species of tree is only found in brightly lit, moist rainforest regions near the equator. An explorer decides to take a sapling back to his home in northern Europe, where he hopes to cultivate it. However, the sapling dies soon after being planted in its new home.
Why did the sapling fail to survive in its new surroundings?
