Close up of a snakes eyes

Can Snakes See? (Evolution of Vision)

Most people have an irrational fear of snakes. The reason probably is that snakes have been represented as the symbol of evil for many years. The appearance of the snakes is most likely responsible for their negative popularity. Along with that, there are hundreds of different myths about snakes in general. 

For example, there is a myth in Kerala that if a person’s shadow falls on a sleeping King Cobra, the snake will identify the person and bite him to death no matter where they go, the Cobra will find them. This myth raises the question; do snakes really have such sharp vision? Can they see and recognise us?

The eyesight of the snakes is extremely poor. They can see the shapes of people or animals but not the details. That is why they stick out their tongue to sense the surroundings. The snakes’ biological evolution history indicates that their lifestyle is responsible for their poor eyesight. As most snakes love to live in dark caves, they do not need to see that much. 

However, there is some exception to this rule. A couple of snake species have developed a habit of catching their prey during broad daylight. These snakes have better vision compared to the others. 

How the eyes of the snakes work

Have you ever wondered how a snake can see to dance when the snake charmers play the music if the snakes cannot see clearly?

Research conducted by London’s Natural History Museum researchers revealed that most snakes only have three different visual pigments. Among these three pigments, the two are in the cone cells, which allow them to see the primary colours. Some species are susceptible to the ultraviolet rays that enable them to see the objects even in low light. 

The snakes that hunt during the day, however, do not rely on the later feature. Their eyes can block the ultraviolet rays, which allow them to see in the bright light. However, the snakes that hunt at night depend on the UV lights to better see their prey. 

Evolution affected the eyesight of the snakes

Most of the studies conducted on the eyesight’s molecular structure and functions have been undertaken on the fishes, mammals, and birds. However, studying the snakes’ vision can give us a fair idea about how the visionary function improved among the vertebrate animals. The reptiles are one of the first species that started to live in the terrestrial condition. Even though we might not see it initially, the snakes’ evolutionary histories, body shapes, and behaviour are very diverse compared to other vertebrates. The vision functions and abilities of the snakes are different among different types. The eyesight of the snakes has evolved depending on their lifestyle.

Amazing Viper Fact: 

A pit viper snake has a fantastic trick to see well at night. These snakes have a pit on each side of their heads. These pits help them to sense heat, just like the night vision goggles. That means their pits, and not their eyes, render images of prey in their brain.

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What makes the eyes of a snake different to other animals

The eyes of the snakes are different from the eyes of most terrestrial animals and birds. Due to their sub-aquatic or underground origins, the snakes have some unique features in their eyes. When the snakes chose to live on the solid land, they had to reinvent their eyes. Even though the snake eyes’ structure is the same as the rest of the tetrapods, their focusing method is, however, completely different. The snakes move the crystalline lens of their eyes backwards and forward to focus on any object. 

Also, they do not have any eyelids to protect their eyes. Instead, they have an ocular scale, known as the spectacle, which gets renewed when they shed their skin. 

The sight adaptation of the snakes largely depends on their lifestyle as well. For example, the more primitive subterranean snakes have quite a straightforward eyesight. They only have rods cells in their eyes while helping them to distinguish darkness from light. 

On the other hand, the diurnal snakes have both rods and cones cells and an utterly round pupil. Like the green vine snake, the arboreal snake has horizontal pupils, allowing a more comprehensive vision range. Horizontal pupils make it easy for the arboreal snakes to calculate the distance between two branches. 

Some kinds of snakes can see lights of other wavelengths as well. For example, pythons, boas, and pit vipers can see the thermic signature around their prey or predators’ bodies. It helps them to find prey at night as they can perceive their body heat.

Clever sense of smell to make up for poor vision

One of the most improved sensory systems of snakes is their ability to smell. It is a well-known fact that snakes use their tongues to detect molecule substances and smell the air. Previously, it was thought that the snakes could only smell through their noses and not their tongues. 

The researchers, however, later proved that the snakes use their nose, as well as their tongue, to smell. However, the tongue is much more useful in sensing in certain situations.

Like other lizards, snakes also have Jacobson’s organ. This organ helps the snakes to detect non-volatile molecule compounds. The snakes flick their tongues against the surfaces or in the air to collect the molecule samples. 

This molecule information is then used for tracking down prey or finding a mate. A recent study has also revealed that snakes can recognise their siblings or other relatives through the smell. The snakes always choose their siblings or relatives first for sharing their hibernation grounds. 

Conclusion

As you have gathered from all this information, the snakes see the world differently than us. They are an essential part of the ecosystem, and thus, it is our responsibility to protect the snakes. For that, we need to understand them a bit better. The more we know their importance, the easier it will become for us to protect them. 

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