Do Animals Need Sunlight? (And How Do They get It?)


Having existed for over five billion years, the Sun is one of the world’s most sustainable energy sources. Although humans haven’t lived for that long, the Sun is vital to all life on Earth, including animals. We rely on it for everything!

Some animals love to bask under the warm rays of the Sun, and others prefer to hide from it. But exposure to sunlight comes with both positive and negative consequences to different animals. Its role in powering the lives of animals is very critical.

Nevertheless, it still makes us wonder if animals need the Sun to survive, and if they do, what happens if they don’t get enough of it? In this article, we’ll provide answers to all these questions. So, keep reading!

Do Animals Need Sunlight to Survive?

The body temperatures of cold-blooded animals such as reptiles and fishes depend on their environment’s temperature. This is determined by the Sun. When the Sun is out, their bodies absorb the heat it generates, which helps them become more active. However, when their environment is cold, they become slower to conserve energy.

Many reptiles and mammals like snakes and lizards also depend on the Sun to become active and increase their body temperatures during the day. Although nocturnal animals such as bats hide to escape the Sun during the day, they indirectly depend on it by feeding on living organisms that derive their energy from the Sun.

However, energy is one of the essential advantages of the Sun for animals. It’s vital to ensure that animals have enough to feed on. Many animals depend on leaves, fruits, and flowers as their primary food source. And without the Sun, these plants can’t get the energy they need to grow.

The Sun is also the primary source of vitamin D for animals, which is essential for their growth. Vitamin D provides calcium, which helps form strong bones and teeth. Animals get vitamin D directly by exposure to the Sun or indirectly by eating plants.

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Finally, sunlight has been found to induce reproduction in some animals, such as birds. In birds, sunlight is used to activate their gonads to start breeding activities, especially during summer when the Sun is out the most. It also helps birds to navigate during migration. And helps other animals determine their hibernation period.  

What Happens to Animals If They Don’t Get Sunlight?

You might think it’s impossible for animals not to get enough sunlight since the Sun shines every day, but various conditions can lead to this. For instance, if you don’t walk your pet regularly or allow them to play outdoor now and then, you’re depriving them of sunlight.

This comes with different consequences for animals. Lack of sunlight will lead to a Vitamin D deficiency, leading to a lack of absorption of calcium in them. It would weaken their bones and teeth.

Photosynthesis will also stop if there’s not enough sunlight. And our ecosystem will collapse. This means there would be no trees, crops, grass, flowers, and fruits for animals to feed on, which would cause a lack of energy and starvation, and eventually, death. Also, without photosynthesis, the carbon cycle can’t occur, which would prevent oxygen from being produced.  

In some other animals, such as cattle, lack of sunlight leads to reduced metabolism and increased melatonin production. Melatonin is the hormone that affects functions such as sleep and aids the animal’s well-being.

Also, lack of sunlight would mean that temperatures would begin to drop, and many animals, including man, that cannot survive in very low temperatures would eventually freeze to death.

How Do Animals Get Energy from the Sun?

Animals get energy from the Sun indirectly. This occurs when they consume plants. The plants convert energy from the Sun into chemical energy and store it in their tissues. This is done through photosynthesis, where light from the Sun is converted into carbon dioxide and water and used to produce sugars in plants.

Some animals rely on plants to get energy; they are herbivores. On the other hand, those that feed on other animals, including herbivores, to get their energy are carnivores. Therefore, carnivores get their energy from the Sun when they consume herbivores.

These animals use the sugars they get from these plants in their mitochondria which are their cellular energy factories. The mitochondria produce energy in Adenosine Triphosphate (ATP), a high-energy molecule that stores all the energy we use.

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Poikilothermic animals, however, enjoy basking in the Sun and so get their energy from it. The Sun, therefore, fuels the energy cycle of both living and non-living organisms.

Do All Living Things Need Sunlight?

We were all taught that every living thing needs sunlight to survive on Earth in school. However, recent studies have shown that even though almost all life depends on the Sun for survival, a few others don’t.

Plants are autotrophs since they produce their own food. They use nutrients from the soil and energy from the Sun to make their food. It means that plants depend on sunlight for their survival.

Herbivores are animals that eat plants and depend on them to survive. This means that herbivores are among the category of life on Earth that can’t survive without the Sun. Carnivores eat herbivores and are highly dependent on the Sun to produce energy for the plants that herbivores eat.

On the other hand, certain autotrophs deep in the ocean have been found to use the energy from the Earth’s core to make their food and not power from the Sun. An example is bacteria that live near jets of hot water that come from deep in the Earth called hydrothermal vents.

These bacteria, called chemoautotrophs, get their energy from the chemicals and heat from these vents; they also don’t need oxygen. It is done through a process called chemosynthesis. Organisms such as the giant tube worm and riftia pachyptila feed on these bacteria and can survive without sunlight.

Do Sea Animals Need Sunlight?

We’ve already established that sunlight is vital for most animals to survive. The difference is that every animal requires different levels of it, and in different ways. The sunlight received even determines the natural habitats of some animals, whether below the sea or on land.

Different sea animals require different levels of sunlight. Some aquatic animals can only afford to live close to the sea’s surface due to the warmth provided by the Sun. Others require the Sun for countershading, which is responsible for the adaptation of some animals like sharks.

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Countershading is a feature of an animal where it is dark on the top and lighter on its undersides. It’s a camouflage tactic; when a predator looks at them from the top, they appear to blend in with the darkness of the waters below. And when a predator is stalking them from beneath, they seem to blend in with the lighter waters above.

Other animals, however, live on ocean floors. They live on ocean beds and depend on dead plants and organisms that sink from the surface to feed. However, the energy provided by these organisms is first gotten from the Sun.

How Can Sunlight Affect Animals Behavior and Activity?

The energy from the Sun has various effects on animals apart from just providing energy for their food. The intensity and duration of sunlight can influence animals’ psychology, behaviors, and morphology.

Most animals have body coverings that protect them from the rays of the Sun. But the solar radiation can penetrate these covers sometimes and lead to activation, heating, and ionization of the protoplasm, which can cause mutations in the DNA of such animals.

Sunlight also affects the movement patterns of some animals. Such animals are phototactic, meaning they either move positively towards the Sun or negatively away from it. Positively phototactic animals include Euglena, Ranatra, etc. While negatively phototactic animals include earthworms, slugs, etc.

The speed of the movement of these animals is also influenced by light. Most animals reduce the rate of their movement when responding to light. Other animals such as arthropods, fishes, and birds use the Sun as a reference to find their way from one place to another. They use the position of the Sun in relation to an established position to do this.

Sunlight also affects the reproduction of some animals, such as birds. Their gonads are activated with increased exposure to sunlight during summer and regress during winter with lesser illumination. Light also improves the development of animals such as salmon larvae and impedes that of animals such as Mytilus larvae.


The Sun is a clean and sustainable energy source, and without it, both living and non-living organisms might not function properly. With the right amount of exposure to sunlight every day, animals can acquire enough energy and nourishment to last them a very long time.

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