Do Ants Have Brains?

Ants have brains which regulate their bodily functions. These brains are small and contain just around 250,000 neurons, a number far less than our 86 billion. This difference is to be expected though, given that ants are small animals.

Their brains however, are relatively large when compared to their body size, much like how it is for vertebrates. And despite being significantly smaller, ant brains work well enough to allow ants to function and be one of the most successful animals in the world.

In this article we’ll discuss the parts and functions of the ant brain and look into their brain structure, size, and plasticity.

Table of Contents

Parts Of The Ant Brain

The ant brain consists of three main segments, the protocerebrum, deutocerebrum, and the tritocerebrum. Each of these segments consist of fused ganglia and control specific activities in the ant’s body.

Protocerebrum. The protocerebrum is the front most segment which contains important parts such as the optic lobes, mushroom bodies, and the central complex. This segment is associated with vision, memory, and other higher functions.

Deutocerebrum. The next segment is the deutocerebrum which contains the antennal lobe. This segment processes different stimuli such as tactile sensations, temperature changes, and odors detected by the antennae.

Tritocerebrum. The last segment is the tritocerebrum. This relatively small paired ganglia connects and integrates the sensory inputs from the prior two. It also links the brain with the rest of the stomodaeal nervous system which controls the internal organs.

Functions Of The Ant Brain

While ant brains aren’t as complex, they still function similarly to ours. Ant brains regulate and govern all the ant’s bodily processes including their movement, senses, and internal organs. More notably, ant brains have the following functions:

Olfactory Processing

Ants rely heavily on their antennae and olfactory system for their general day to day tasks. These antennae are full of sensilla which sense a wide variety of stimuli including physical, chemical, and other stimuli which allow ants to detect vibrations, chemical odors, and even temperature changes.

Majority of these sensilla are connected to receptor neurons which receive and send information to the brain. From there the brain processes such information to precisely distinguish the odor and allow ants to respond accordingly.

For example, ants are able to distinguish complex hydrocarbons which allow them to identify friend from foe. The lack of or presence of certain odors in other ants may cause ants to react aggressively.

Ants also use these odors to detect different types of pheromones which they use to communicate. Pheromones for instance, could be used to indicate successful food finds, identify dead ants, and as an attractant during mating. The brain processes and discriminates between these different chemical signals so as to trigger the correct response and behavior.

Visual Processing

While not as developed as their olfactory system, some ants still rely on vision to understand their environment and to detect the changes that occur in it. Apart from subterranean ant species, ants generally have simple eyes called ocelli or compound eyes which allow them to see.

In these eyes are photoreceptors which convert light into inputs that get sent to the brain. The brain then processes these inputs and extracts color or motion information which ants can then use for navigation, foraging for food, and to react to potential threats like predators.

Memory And Learning

The mushroom bodies found in the protocerebrum of the ant brain play a role in learning and memory. They integrate different pieces of sensory information from the olfactory and visual system to allow ants to pick-up and interpret chemical cues and visual input.

For example, mushroom bodies allow ants that rely on visual cues to use terrestrial and even celestial cues to memorize the landscape of a specific environment.

Orientation And Movement

The central complex in the ants’ brain receives inputs from the mushroom bodies and integrates different sensory inputs to modulate motor commands and control the ants’ legs and wings. This important part of the brain allows ants to move and orient themselves appropriately.

Differences In Brain Structure Between Ant Castes

Division of labor is a key characteristic of eusocial insects like ants. As such, their colonies consist of three different castes, each of which have special roles reflected in their brain structures.

For example, male ants which don’t actively participate in colony building and are instead specialized just for the mating flight and reproduction tend to have relatively larger ratios of optic lobes and central complexes compared to queens and worker ants. This means their brains are more specialized for visual processing and locomotion.

On the other hand, both female castes which maintain and grow the colony tend to have larger ratios of antennal lobes and mushroom bodies which help them process sensory information from their antennae.

There are also differences in brain structure of workers and queens. Workers, which bear the responsibility of nest management and maintenance have a larger ratio of mushroom bodies which again relate to sensory integration, memory, and learning. This helps them navigate as they forage and communicate with their nestmates.

As for queens, those that participate in mating flights tend to have a larger ratio of optic lobes when compared to workers.

Differences In Brain Size And Brain Plasticity

Apart from structure, brain size also varies between species and ant castes. At the species level, brain size is usually determined by the size of the species. This means that on average, larger ants tend to have larger brains.

As for ant castes, brain size depends on behavior and the need for neural processing. Worker ants for example, tend to have larger brains compared to male ants because of their need to use their brains when foraging and maintaining their nests.

Ant Brain Plasticity

In relation to brain size and behavior, research has found that ant brains may either increase or decrease in size depending on behavioral changes.

For example, the mushroom bodies in worker ant brains increase in size when workers transition from working inside the nest to becoming foragers. This may be due to the increased demand of brain power which then in turn gives rise to the modification, growth, and addition of synapses in the ant brain.

In contrast, when worker ants transition into gamergate (reproductive worker ants), their brains shrink around 20 to 25% in size. They selectively lose parts of their brain used for hunting, foraging, and general critical thinking to focus their bodily resources to their ovaries.

Research has also found that they can regrow their brains back to their previous size when they turn back from gamergates into workers.

Summary: Do Ants Have Brains?

Ants have relatively less complex brains that provide just enough processing power to allow them to process a variety of stimuli from their visual and olfactory system, learn and memorize important information, and lastly, orient and move themselves accordingly.

All in all, their brains allow them to become one of the most successful animals in the world.

Do Ants Have Brains?

Parts Of The Ant Brain