How Many Eyes Do Ants Have? A Detailed Look

Ants are ubiquitous insects that have colonized almost every landmass on Earth. If you’ve spent any time outdoors, you’ve likely encountered the hurried march of these tiny six-legged creatures. Given their small size, have you ever stopped to look closely at an ant’s face and wonder – how many eyes do ants have?

If you’re short on time, here’s the quick answer: most ants have two compound eyes, each composed of many miniature eyelets that give them a mosaic view of the world.

In this approximately 3000 word article, we’ll take a closer look at ant eyes. We’ll cover ant eye anatomy, comparing simple vs. compound eyes across insect species. Delving deeper, we’ll explore how ants use their eyes and other sensory organs to navigate, locate food, and communicate.

We’ll also answer some common questions about ant eyesight and vision capabilities. By the end, you’ll be an expert on the tiny yet complex optical systems of these abundant insects.

Ant Eye Anatomy

Typical Ant Eyes

Ants have two compound eyes, each containing many individual hexagonal lenses called ommatidia. Each ommatidium contains a cone of visual cells surrounded by pigment cells. This structure allows each ommatidium to function as an independent visual receptor (1).

The number of ommatidia can vary greatly between ant species, from as few as 10 to over 1,000 per eye (2)! Generally speaking, ants that are active during the day (diurnal) have more ommatidia than nocturnal species.

Having many small lenses instead of one large lens provides ants with a wide field of view to help detect predators and navigate terrain. However, it comes at the cost of visual acuity – images perceived by the ant compound eyes are low resolution compared to human eyes.

Each ommatidium has a fixed field of view, so the more ommatidia an ant has, the better its vision. The tradeoff is that packing in more ommatidia results in smaller individual lenses, which detect fewer photons of light (3).

Ant eyes are also incapable of forming sharp images. Their vision is blurry even at short distances. Still, it suits their small size and natural behavior. Ants rely primarily on senses like touch, smell and taste to interact with the immediate environment.

Vision helps them navigate back to the nest from distant food sources using landmarks (4).

Eye Composition and Function

The principal light-sensing cells in ant eyes are the retinula cells in each ommatidium. These contain light-sensitive opsins, similar to human photoreceptor cells (5). When opsins absorb light, they trigger neural signals that the brain interprets as visual information.

Each ommatidium also contains a transparent cornea, a crystalline cone that focuses incoming light, and a light-absorbing pigment sheath to isolate it from neighboring ommatidia (6). Adaptations in these structures improve vision in different ant species:

• Day-active ants often have corneas with deeper lenses and larger crystalline cones to focus more light.
• Night ants may eliminate the pigment sheath to capture more light from adjoining ommatidia.
• Some ants have yellow filters in their ommatidia to improve contrast and motion detection.

Rather than forming images, ants likely perceive changing patterns of light and dark spots detected by their many low-resolution ommatidia. Their wide field of view gives them superior motion detection to sense prey, rivals, and obstacles (7).

In this way, ant eyes beautifully complement their small size and active lifestyle.

Ant Eyes vs. Other Insect Eyes

Simple Eyes

Ants, along with some other insects like flies and beetles, have simple eyes known as ocelli (singular ocellus). Ocelli consist of a tiny lens, light-sensing cells, and a retina. They can only detect changes in light intensity, allowing the ant to perceive if it is in dark or bright conditions.

Ants typically have 3 ocelli arranged in a triangle pattern on the top of their head. These give ants a very rudimentary, low-resolution sense of vision.

Compound Eyes

More advanced insects like flies, butterflies, bees, and dragonflies have compound eyes instead of simple ocelli eyes. Compound eyes are made up of thousands of tiny lenses called ommatidia, with each lens having its own light-sensing cells.

This gives insects a mosaic-style vision with more clarity and depth perception compared to ocelli, but still relatively poor resolution. According to entomologists, compound eyes are useful for detecting quick movements which helps insects evade predators or track prey.

Ocelli

In addition to compound eyes, most flying insects and some ants retain a few ocelli as well. For example, honey bees have 3 ocelli on top of their head in a triangle, which assists with stability in flight through horizon detection.

Carpenter ants may also have 1-3 ocelli nestled between their compound eyes that aid in detecting diffused light. So ocelli still serve a helpful supplemental purpose despite compound eyes being more advanced.

How Ants Use Their Vision

Food Searching and Foraging

Ants heavily rely on their sense of smell to locate food sources. However, their eyes also play an important role while foraging. Workers use their vision to identify objects in their vicinity and determine if they are edible or not.

Their compound eyes, which consist of numerous tiny lenses, give them a wide field of view to scan the environment. This helps them efficiently scan a large area to pinpoint food items like sugary secretions from plants or crumbs left by humans (1).

Navigation

In additional to chemical trails, ants also use visual cues for navigation back to their nest. Landmarks such as large rocks, trees, and shrubs serve as guideposts for orienting themselves. Their vision helps them recognize these familiar landmarks during their foraging journeys away from the nest.

Scientists have discovered that ants memorize panoramic snapshots of the surrounding landscape as seen from their nest entrance. This allows them to determine the direction back home by comparing their current view with the memorized snapshots (2).

Communication

Ants have poor vision compared to humans. However, their eyes are sensitive enough to detect visual signals from other members of the colony. When encountering each other, ants frequently tap their antennae together.

During this antennal contact, they use their vision to identify individuals of the same colony based on a distinct colony scent. Visual signals are also used to indicate sources of food or danger. Scout ants finding an abundant food source will return to the nest in an excited state, running in a zig-zag pattern.

This behavior communicates information to other ants who see the scout, prompting them to follow it to the food source (3).

While ants have simple eyes, their vision does play important roles in foraging, navigation and communication. Their specialized compound eyes allow them to efficiently scan the environment for food and threats as well as pick up on visual cues from other ants.

Ant Eye Capabilities and Facts

Visual Acuity

Ants do not have great visual acuity compared to humans and other animals. Most ants have compound eyes made up of multiple facets that detect light and movement rather than clear, focused images like humans.

Their compound eyes give ants a wide field of view but lack high-resolution vision to see details (Penn State Extension). For example, the average ant can only distinguish objects clearly when they are < 2 millimeters away, which is equivalent to humans seeing clearly at a distance of about 2 meters, according to some estimates (Ask an Entomologist).

However, there is variability among ant species in terms of visual acuity. Some ants that rely heavily on vision like bulldog ants and trap-jaw ants have better eyesight. Studies on bulldog ants found they can learn to associate visual patterns and run maze experiments, indicating better visual processing skills (Schwarz et al.

2011). Still, even ants with better vision do not process clear, high-resolution images like humans. Their small compound eyes are better adapted for detecting motion and sudden changes in light to navigate their environments.

Color Detection

Most ants cannot detect color like humans can with specialized cone cells. Instead, their compound eyes likely only detect colors in grayscale ranging from ultraviolet to green wavelengths of light (CABI Invasive Species Compendium).

Several ant species like the Florida carpenter ant are more sensitive to UV light compared to visible light wavelengths. UV sensitivity may help ants use the polarization of UV patterns in the sky as a navigation cue (Somanathan et al. 2008).

There is some evidence of color sensitivity in a few ant species. For example, one study found the Australian bulldog ant Myrmecia pyriformis was able to associate color cues like blue and yellow with sugar rewards (Schwarz et al. 2011).

The researchers indicated M. pyriformis may have color sensitivities on par with bees. However, most ant species lack strong color vision and rely more on detecting light intensity differences.

Night Vision

Most ants are diurnal and rely primarily on vision during the daytime. However, many ant species switch to increased reliance on their antennae and chemical senses to navigate at night. Species like fire ants (Solenopsis invicta) exhibit circadian rhythms tied to daily light/dark cycles, becoming more active at night (Sauer et al.

2000). To help with navigation at night, some ants may use visual cues from moonlight and star patterns (Ask an Entomologist).

Other primarily nocturnal ant species like the grey ant (Aphaenogaster araneoides) may have adaptations to help them see better at night. One study found the grey ant has a 100-fold increase in visual sensitivity compared to diurnal ants, allowing them to navigate and forage using dim moonlight (Warrant et al.

2017). Enhancements to their eyes like wider aperture and specialized light-sensitive channels help grey ants see well in dark conditions. Still, the visual capacities of most ants drop off significantly at nighttime.

Common Questions about Ant Vision

Can All Ant Species See?

The answer is yes – all ant species have eyes and the ability to see. Ant eyes are compound eyes, meaning they are made up of many smaller units called ommatidia. Each ommatidium contains a lens and functions as an individual visual receptor.

This gives ants a mosaic-type vision with each ommatidium perceiving one small part of the whole picture.

Different ant species have varying numbers of ommatidia, from as few as 5 to up to 1000, allowing them to see images at different resolutions. For example, driver ants, who need to see well as they march in large colonies, have up to 1000 ommatidia while ants living underground may only have around 11.

Do Ants Ever Lose Vision or Go Blind?

It is rare but possible for individual ants to lose vision or go blind. This can happen through injury, age, or genetic issues. As ants rely heavily on pheromone signals from other colony members, a single blind ant can usually still function fairly normally within the colony.

However, any tasks requiring vision like foraging would be difficult.

In some ant species, all of the worker ants are born completely blind and rely 100% on pheromones to interact. An example is the Atta colombica leafcutter ant. Their worker ants are born without eyes, but the queen and male drones have normal vision.

Do Ant Eyes Change Over Their Lifespan?

Ant eyes do undergo changes as they develop and age:

• Larval ants have simple eyes (stemmata) which allow them to sense light levels but not see detailed images.
• Once ants pupate and transition to adults, their full compound eyes form within the pupal casing.
• The number of ommatidia in an ant’s eye grows as they mature, improving resolution.
• In old age, vision declines as ommatidia lose function and are not replaced.

So ant eyes improve through young adulthood and then slowly degrade in later life. The extent of growth and decline depends on the ant species. For ants with naturally short life spans, their eyes may never substantially degrade.

To learn more on the anatomy behind ant eyes and how they function, check out this detailed guide on AntArk.net.

Conclusion

As we’ve explored, ants have two large compound eyes that give them a mosaic view of the surrounding world. Their eye anatomy and vision capabilities are perfectly adapted to their ecological roles – allowing them to navigate diverse terrain in search of food and resources critical to the ant colony’s survival.

While tiny in size, ant eyes are complex structures with hundreds of individual visual receptors coordinated into a cohesive visual system. Ants continue to see, learn, and work together throughout their adult lifespan thanks to these intricate but durable organs.

Next time you spy an ant scurrying by, consider taking a closer look at those two dark spots on either side of its head. Understanding the insect eye gives us appreciation for ant capabilities as well as inspiring innovations in human visual technologies.