How Many Eyes Do Flies Have? Crazy Facts You Won't Believe

A lot of people think that flies have as many as a thousand pairs of eyes.

But, when you look at a fly, it has only two eyes. So how can this tiny insect have thousands of eyes?

Does this mean that they are lying? Well, they are correct in their perspective. Would you like to know more about it?

A fly has only two eyes, but these two eyes are equivalent to thousands of eyes. You will get to know more about fly eyes in the latter part of the article. A fly does not have eyes like us.

Flies have compound eyes. Compound eyes are eyes that are made of thousands of eyes. We will discuss this later in detail.

But have you ever tried to catch a fly? Have you ever wondered how a fly with such small eyes can see you coming towards it and quickly fly away from you? Well, you will find the answers to these questions in this article, where we will share all we know about flies' eyes.

After reading all about how flies look at objects, do read how many eyes do bees have and how many legs do insects have.

What are compound eyes?

Compound eyes are types of eyes that most arthropods have. These eyes consist of thousands of photoreceptors that help the vision of insects and crustaceans.

Almost all species of insects like flies and bees have these compound eyes. A compound eye forms a three-dimensional image which is a combination of thousands of images received by thousands of photoreceptors present in a single compound eye.

Did you know that the resolution of the image formed by a compound eye is quite low compared to the image formed by a single aperture eye?

Instead of this low image quality, compound eyes give flies and other insects a large area of vision to see and the ability to detect the movement of every object close to them.

This helps flies to respond quickly to any kind of movement nearby.

This is the reason why you cannot catch a fly so easily. They can detect even the slightest movement quickly and respond accordingly.

There are mainly two types of compound eyes. The first is apposition, and the other is superposition. Apposition eyes form multiple inverted images, while superposition eyes form a single image. Flies have special compound eyes, which provide them with better vision than most insects.

Do you know how many eyes flies have? A fly has two large compound eyes, which are equivalent to a thousand eyes.

How many lenses does a fly have?

A compound eye contains thousands of lenses. Do you know how many eye lenses you have? You have only two eye lenses, with one in each eye.

Our eyes provide a high-quality resolution through which we can see almost every detail of the world that we need to see. Flies have eyes different from ours. They have compound eyes, and compound eyes cannot provide a high-resolution image.

Then how can flies respond so quickly to our slightest movement? A fly has a pair of large compound eyes and each of them consists of 4000-4500 individual lenses combined together.

This is a lot of lenses. No wonder why people say that flies have thousands of eyes. To be precise, flies do not have thousands of eyes; they just have thousands of lenses in their eyes.

This provides them with a very wide vision to see. Well, now you have the answer to the question of the number of eyes of flies.

The lenses of compound eyes form images of all the surroundings of a fly. They give them the information of what is in front of them, what is at their right, what is at their left, and what is top of their head, all at the same time.

The images which form in a fly's head are three-dimensional, which makes it difficult for us to catch them, and easy for them to catch their prey.

Flies do not have simple eyes, which are called ocelli. Ocelli eyes are specialized in detecting the movement of any object in a specific manner.

But, the compound eyes of flies are also well developed to detect motion and save them from threats. Ocelli act like a compass by keeping track of sunlight. This lets the fly move around easily.

Structure Of An Ommatidia

Let's talk about the structure of ommatidia. But, first of all, what is ommatidia? Ommatidia are the photoreceptors that contain clusters of photoreceptor cells.

A compound eye contains thousands of ommatidia. These are the fly's thousand eyes. A single ommatidia is called an ommatidium, and each ommatidium has a cluster of photoreceptor cells, which are surrounded by many support cells and pigment cells.

Ommatidia usually look hexagonal in shape when seen through a cross-section. Do you know that an ommatidium is ten times longer than its width?

Ommatidia are conical in shape, with the largest diameter at the top and then shorter inwards. The structure of ommatidia contains the following parts: cornea, crystalline cone, pigment cells, rhabdom, photoreceptor cells, membrana fenestrate, and optic nerve.

Flies and bees have specialized zones of ommatidia which provide them with acute vision. These acute zones are flattened, and this flattening provides an image with higher resolution compared to other insects. So, flies and bees can see more clearly than other insects and this makes them some of the best flying insects.

Function Of Compound Eyes

The main function of compound eyes is the function for which eyes are made. That is to see the world.

A fly's compound eyes make it able to see the world, not for its beauty, but for its own survival. Flies are such small insects that it is so hard for them to live in a world full of such giant creatures like animals, birds, and humans.

Flies also fear different types of danger, such as being eaten by predators.

So, they need great vision in which they can see everything in their front, back, left, right, and even above their head at the same time. Compound eyes serve this purpose to flies.

Compound eyes function as photoreception units to get information about what is happening around them. These eyes provide such a good resolution of image to flies that they can observe their surroundings in a detailed manner.

Also, compound eyes provide information on the movement of anything around them, so they respond with such a speed when someone tries to catch them.

Compound eyes also help in finding prey. Since flies have such nice vision they can detect their prey with ease. Fly's eyes can also detect the polarization of light and different color spectrums which are not visible to even human eyes.

It seems that flies, being so small, cannot see the world as we do. But, flies have better vision than most big animals and even humans, not in terms of resolution but in terms of the color spectrum.

Many species of big animals lack the ability to differentiate between specific primary colors, and this tiny insect can see the world in quite a varied spectrum of colors.

Here at Kidadl, we have carefully created lots of interesting family-friendly facts for everyone to enjoy! If you liked our suggestions for 'How many eyes do bees have?' then why not take a look at'How many legs do butterflies have?' or 'House Fly facts'.