Take a look at even the strangest creatures in the world, such as the shape-shifting, poison-wielding, flashing-skinned flamboyant cuttlefish, and we can normally still relate to them in some way. They are individuals, like us, after all. They are driven by the same basic instincts – food, safety, reproduction and an insatiable need for moving lights, even if theirs is on their skin and ours is on our smartphones.
A colony of ants, however, seems truly alien because of their group consciousness, sometimes called the hive mind. Ants don’t act for themselves, they act selflessly and continuously in service of their colony, to the point where an ant which deliberately explodes itself as a sacrificial defense tactic for its comrades has been discovered.
Given how alien and strange ants can seem, it seems reasonable to ask if they do anything that we can relate to. Do they have sex in any way we understand? The anwer is yes, they do, but not all of them – the worker drones who we normally see are all females, but without any prospect of mating or reproduction given the queen’s total monopoly on this behaviour. An even more fascinating question, especially given their apparently ceaseless busyness is this:
Do Ants Sleep?
Though there haven’t been many studies done into this sleeping behaviour, most of which is hidden from us inside their nests.
Ants have been observed anecdotally by antfarm keepers to take brief power naps while away from their nest, but these are rare and most sleep takes place in the nest.
Because they are underground and always dark, the concept of night and day seems to be irrelevant to ant sleep, though it seems obvious that nocturnal species will sleep more in the day while day-roving species will sleep more at night.
This hints at the fact that there may be massive variance between different ant species, which are certainly not identical. You’ve just met the exploding ant, which is very different from the species of ants which can form a raft by bonding together and travelling by water and which is very different again from the “mass murder ant” (Crematogaster striatula) which are in an eternal and incredibly savage war with termites, including the use of chemical weapons. It wouldn’t be a surprise to also see huge variance in sleeping patterns between species.
The earliest significant research into the matter was conducted by conducted by James and Cottell in 1983 and suggested that red and black ants both have cyclical patterns of resting periods which each nest observes. These appear to be quite brief, lasting just eight minutes in a 12 hour period. Even then, only one of these 12 minute sleeps appears to be true sleep, which is observed by noticing a 65% decrease in mandible and antennae activity, and backed up by monitoring brain activity which appears to dip sharply during this deep sleep. Fascinatingly, soldier ants brain activity seemed to increase during the sleep, which might suggest that they are in fact hyper alert to defend during a period of vulnerability. Or perhaps they are just dreaming of war and mayhem?
In the early 21st century a more controlled study was undertaken by Deby Cassill, Skye Brown and Devon Swick of the University of South Florida, along with George Yanev of the University of Texas to study the sleeping patterns of the fire ant Solenopsis invicta. After years of rumours of the queen ant’s legendary laziness, the group decided to find out the facts and raised a colony of fire ants in their laboratory, including an artificial chamber containing three queens, 30 workers and 30 large larvae.
What they quickly found was that workers fell asleep at irregular intervals, taking the equivalent of a power nap. These last less than a minute for the most part, and are incredibly frequent. Typically a worker ant would take around 250 naps a day, adding up to around 5 hours of sleep a day. Rather interestingly, this is almost the exact same sleeping routine as a giraffe, which is about as unlike an ant as another animal could possibly be in every other way.
What does seem to be true for these apparently random ant naps is that they are in fact not random at all. They were somehow arranged in such a way that 80% of the workforce was awake and active at any one time, ensuring that the nest is maintained, the lazy queen satisfied and any attacks defended at any point.
How long do queen ants sleep?
As always, there is one huge exception in the ant universe: the queen. Returning to our South Florida study, the researchers found that queens – freed from the need for work – fell asleep much more deeply and for longer periods. A queen would typically take 90 naps a day, sleeping for just over 6 minutes each time, equating to double the amount of sleep for a worker. They appear to be able to sleep in a dozing state like their workers, where their antenna are half raised and their mouths unseemingly agape. In this light sleep they can easily be roused by their workforce if necessary.
At other times, however, the queens would fall into deeper sleep, antennae retracted and mouths closed. This could well be linked to the fact that they can outlive their workers by a factor of 12, able to make the grand old age of 6 compared to the workers’ 6 month life spans. Fascinatingly, Cassill’s team believed they had evidence that the queen ants dream in this state. Frequently, the queens would quiver their folded antennae when in deep sleep, a possible insect version of the rapid eye movement in deep sleeping vertebrates (like us!). This leaves us with one final tantalizing possibility. While those selfless, robot-like, dreamless worker robots may feel entirely alien to us, could that lazy, sleepy queen full of dreams be rather closer to us than we might like to admit?
What other animals have weird sleeping habits?
There are other insect species which take a very different approach to sleep, one much more like our own. They are usually either diurnal or nocturnal, meaning active in the day or the night. During those periods where they are not, most insects – like the common fruit fly – fall into a still state which is certainly akin to sleep and which we call “torpor”. Butterflies seem very dependent on sleep and need a lot of it to be able to function well, which may be unsurprising when you see the beautiful, flamboyant and yet rather inefficient way with which they fly. Other insects, including termites, appear to follow the frequent nap approach pioneered by ants.