Ants do have a heart, like all insects, however, it looks and functions very differently from our own. An ants’ heart is long and thin and pumps the ant’s haemolymph (blood) from one end of the body to the other.
What is a heart for?
In humans and many other animal groups, the heart has a very clear function. Its rhythmic pumping helps to force blood around the body, delivering oxygen to the various organs. Without the constantly moving blood, our organs would become starved of oxygen, and begin to die.
|Ants||Open circulatory system||Pumping hemolymph (insect “blood”) to distribute nutrients, oxygen, and hormones throughout the body|
|Humans||Closed circulatory system||Pumping blood to deliver oxygen and nutrients to organs and tissues, and removing waste products|
|Earthworms||Closed circulatory system||Pumping blood-like fluid (hemolymph) through vessels to transport nutrients and oxygen|
|Fish||Two-chambered or three-chambered heart||Pumping blood through gills to obtain oxygen and distributing it to the body|
As well as transporting oxygen-rich red blood cells, which give blood its brilliant scarlet colour, blood acts as a vessel for all kinds of other ingredients, from delivery of vital minerals and vitamins to removing unwanted waste.
The human heart is probably one of the easiest organs to recognise, its rounded form and two chambers made famous by horror movies and science shows alike. Yet within an insect’s chest, a whole different system has been set up to perform a very similar function, one that we would barely recognise.
Do ants have a heart?
Insects have a very different circulatory systems to that of humans. The difference starts from the most basic element, with the blood. The fluid that moves around insects’ bodies, which is the equivalent to our blood, is called hemolymph.
Unlike our blood, haemolymph isn’t red. This is because it doesn’t contain red blood cells. The reason insects lack these cells is that their blood doesn’t need to transport oxygen around their bodies. In most animals’ bodies, the air is drawn into the lungs, and from the lungs, it is absorbed into the blood.
|Queen||Well-developed heart||Pumping hemolymph to circulate nutrients and oxygen throughout the body, supporting egg-laying|
|Worker||Simplified heart||Assisting in circulating hemolymph for nutrient distribution and waste removal|
|Male||Reduced or absent heart||Less emphasis on long-term maintenance, as males’ primary role is mating|
The blood then moves around a closed circulatory system, meaning that the blood travels to organs via arteries and veins. In insects, the blood doesn’t need to carry the oxygen to the organs because air doesn’t enter into the body at one point.
Instead of one set of lungs, insects have many spiracles along with their bodies, small holes within their exoskeleton through which air is drawn into the body. Once it enters the body, it is fed directly to where it needs to go, rather than needing to be circulated.
The haemolymph in an insect’s body, therefore, plays a very different role to the blood in ours. Rather than carrying oxygen, it simply carries other ingredients such as minerals, sugars and hormones to the various organs.
Another key difference between our system and that of insects is that their circulatory system is an open system, while ours is closed. That means that within our bodies, blood is ferried around within veins and arteries. Within insects, the haemolymph simply fills the body cavity, surrounding the organs and fats that fill the rest of the space.
However, there is one part of the system that is closed, this is the dorsal vessel. The dorsal vessel is a long, thin tube that runs from one end of the insect to the other. It pumps the haemolymph towards the head of the insect, it then circulates back through the body cavity, before being pumped around again through the dorsal vessel.
|Environmental Condition||Heart Function|
|Normal conditions||Steady heartbeat rhythm to maintain circulation of hemolymph throughout the ant’s body|
|High activity or stress||Increased heart rate to support increased oxygen and nutrient demands|
|Low temperature or hibernation||Heart rate and metabolic activity may decrease to conserve energy and survive harsh conditions|
|Injury or infection||Enhanced heart activity to facilitate immune responses and deliver immune cells to the site|
The dorsal vessel is divided into two parts. The length closest to the head is the aorta, while the second part is considered the heart. In terms of shape, the aorta and the heart don’t differentiate much, both being long thin tubes, however, what separates the heart is the presence of chambers divided up by Ostia.
Additionally, smaller pumps exist at the base of some appendages, such as antennae and wings, in order to push the blood into these areas. The heart tends to be located within the abdomen, the final segment of the ant’s body. This is where all the vital organs are kept. The aorta extends the rest of the way to the head.
A heartless ant
We have a tendency to think of ants as tiny wind-up toys, busy about their business, but not alive in the same way we are. We might feel guilty if we accidentally hit a pigeon in our cars, but few people feel bad when they step on an ant.
Yet, just like all living creatures, ants do have a heart-pumping within their bodies, moving round blood that is not so dissimilar to ours. They may be different from us in many ways, but their bodies are still busy keeping them alive, just like ours.