Flies are small insects commonly found around the world. They belong to the dipteran family, which means two-winged. About 120,000 species of flies are known to exist, and the majority of them possess astonishing visual abilities.

Flies are equipped with a remarkable visual system that allows them to see and orient themselves in their environment with extreme accuracy and precision.

Basic Anatomy of Fly Eye

The eyes of flies are complex structures that allow them to perceive the world around them in great detail. These eyes are made up of thousands of tiny lenses known as ommatidia.

Each ommatidium has its retina, lens, and nerve fiber, with each ganglion cell taking input from just one receptor. Collectively, ommatidia create an image on the fly’s brain that enables them to detect the direction, color, contrast, and speed of objects in their environment.

One of the most fascinating aspects of the fly eye is that it can detect movements at an incredible speed, even up to five times faster than a human.

This is due to the number of ommatidia present in the eye, which allows the flies to create a ‘patchwork’ image of their surroundings, enabling them to see up to 360 degrees in all directions.

Compound Eyes

The eyes of a fly are classified as compound eyes, which are composed of many sub-eyes or ommatidia. The arrangement of these sub-eyes in the eyes of a fly allows them to have a panoramic view of the world around them.

Each ommatidium has its refractory lens which helps it to focus on the environment. The retina of each ommatidium contains cone-shaped photopigment cells, also known as rhabdomeres. These cells are responsible for converting light signals into electrical signals that are then sent to the brain to be processed.

Another notable feature of the fly eye is that it can detect polarized light, which allows them to navigate their environment.

They use this polarization sensitivity to detect the position of the sun, which they use as a reference to navigate and avoid predators.

Color Vision

Flies possess phenomenal color vision that enables them to see the world in very bright colors.

Unlike humans, who have three photoreceptor types capable of discriminating between different wavelengths of light, some fly species have five photoreceptor types. This additional type of photoreceptor enables them to distinguish between different shades of UV light beyond our visual range, which is why some flowers and fruits appear differently to flies than to humans.

Visual Perception

One of the significant advantages of the compound eye is that it provides a considerable field of vision, which is essential for escape mechanisms and prey location.

For example, if flies see an approaching predator such as a spider or a bird, they can detect this from the shifting patterns and motion of the predator’s movements. Flies use this information to move quickly away from the predator, which is why they are often difficult to catch.

Aside from detecting predators, flies use their incredible visual perception to find mates, locate food sources, and evaluate the resistance of surfaces while they are walking.

Their visual system provides them with a near-instantaneous analysis of obstacles in their environment, allowing them to react quickly when they encounter new and unfamiliar situations.

Conclusion

Flies possess a remarkable visual system that allows them to detect the direction, color, contrast, and speed of objects in their environment with extreme accuracy and precision.

Their compound eyes are the most advanced and complex among insect species, and their perception capabilities have played a significant role in their survival.