Are worms blind? (Can Earthworms See or Sense Light?)

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Unlike having eyes on their front ends like fish, snakes, birds, or other animals in nature, worms have their own means of getting around. Instead of eyes, worms have certain other things to help them to understand, use, and leave their environment, when necessary while being technically blind. 

Technically, yes worms are blind. That is to say that they do not have eyes. However, that does not mean that they cannot efficiently navigate their surroundings.

In this article, we will see just how worms “see”, how their means for movement and choice of environment are all connected to their sight, and more.

Can Worms See Light?

Worms cannot exactly see light, but they can sense it.

As it happens, worms do not possess eyes like other animals do.

Instead, worms possess light receptors that help them to detect whether it is light or dark, and whether or not they are above or below ground.

These special cells, also called photoreceptors, are situated all over the worm’s skin. 

These receptors are crucial to a worm’s survival, as their location will need to vary frequently for their survival (as is the case with most living things). 

For example, if a worm senses other creatures around them, or that rain is falling, they will need to surface to the top of the ground.

First of all, due to the fact that these other animals could be predators, and due to the fact that the worm will not want to be in an environment that is too wet for too long. 

Being able to sense where the light is is also essential when it comes to avoiding the light. Earthworms live in the soil for a reason.

It is partially due to the fact that they should not be in direct sunlight for too long. Within approximately one hour of direct sunlight, a worm will die.

This is due to the fact that their very sensitive skin will dry out, and thus suffocate them. As worms breathe through their skin, it is essential for them to constantly be in a moist area.

This is why in compost piles and vermicomposting systems, it is so important to also keep the bins moist. 

Do Worms Have Good Eyesight?

Although worms do not have eyes specifically, they do have very practical receptors. 

These photoreceptors are naturally very sensitive to light, but they are also very sensitive to touch. Worms respond well to various senses, as it happens.

The worm’s body will use its receptors to ensure that they are in a dark enough area, and therefore well within the soil, at all times.

In fact, they will only use their receptors to reach the surface of the soil if, through the very same receptors, they sensed disconcerting vibrations, chemicals, wetness, etc.

Some even believe that these receptors provide a sense of taste to the worms, and possibly even a sense of smell to help them to locate where they will next find their food source. 

Whatever the case, there is no denying that these receptors are essential to a worm’s survival, and, due to the species’ longevity, they are also proven to be extremely proficient in their job.  

How do worms sense light?

As previously stated, worms sense light through photoreceptors in their skin.

These photoreceptors are connected to nerves called Ganglia, which in turn are connected to the ganglion i.e. the worm’s brain). 

The worm’s brain sits next to the worm’s other organs, connecting the nerves from the skin, and their muscles. 

It is thanks to the ganglion that worms respond adequately to their surroundings, thus ensuring that they eat the right nutrients, have enough oxygen, and are more adept at avoiding various types of animal species.

It is also thanks to their brains that they have the ability to contract their circular muscles and release their bodies, thus moving forward in, or on the earth. 

Summary

So, are worms blind? Although they do not have eyes like we do, it would be a mistake to simply call worms blind.

In the same way, for example, it would be like saying that as worms do not have legs, they cannot move. 

Worms can move just as efficiently as they can navigate their surroundings. 

In fact, Charles Darwin came to understand just how impactful one earthworm can be on its environment by burrowing through the soil, as they aerate the ground. 

We have come to understand, too, that worms would not be able to burrow in such an efficient way without the photoreceptors that they use as eyes to navigate the ground.

These receptors help them to ensure that they are always in a safe, and comfortable environment and that they are heading towards the very nutrients that they need to feed the soil with their castings.