Kevin Healy, University of Galway
February 24, 2026
As you read this, the screen is probably flashing over 240 times per second, yet, as a human, you won’t notice this flickering light.
However, to a fruit fly hovering above your head, the screen would represent a strobe light fit for an Ibiza rave. This is because the way different species sample time, and the rates at which they can perceive it, varies greatly across the animal kingdom.
To us, a fast moving ball might seem like a blur but to dragonflies, pigeons and even bigclaw snapping shrimp it can be seen in great detail. But for species like snails or certain deep sea fish, like the escolar, the motion is probably too fast to register at all.
But why do animals perceive time differently?
To understand why, my colleagues and I collected published measures of time perception across the animal kingdom and analysed them. Our analysis showed this variation in time perception is largely driven by the pace of a species’s lifestyle.
Devices, such as electroretinograms, can measure time perception. The electroretinogram does this by recording the electrical activity of the retina in response to a flashing light. Gradually increasing the rate of flicker until the animal can no longer see the flashing can help scientists determine the limit of its time perception (scientists call this an organism’s maximum critical flicker fusion rate).
Our analysis showed that temporal perception has even greater variation than scientists may have realised. Our perceptual limit as humans is approximately 65 flashes per second. However, birds, such as the collared flycatcher, can see up to 138 flashes per second while tsetse flies and dragonflies can distinguish up to 300 flashes per second.
At 65 flashes per second (or Hz), humans display respectable temporal perception abilities compared to other animals. It is higher compared to many mammals, such as rats at 47 Hz, but slightly lower than dogs (84 Hz).
Our eyes seem even more respectable when compared to the slowest eyes in the animal kingdom, such as the deep sea fish, the escolar, which can only perceive 12 flashes per second or the most extreme cases of the crown-of-thorns starfish and giant African snail, both of which can only perceive 0.7 flashes per second.
But why does a dragonfly have such fast eyes while starfish are confined to a world of vision blur? One idea, called Autrum’s hypothesis, is that time perception costs a lot of energy and the evolution of such fast visual systems will only emerge in species with fast paced lifestyles.
Our analysis showed strong support for this idea, with the highest rates of temporal perception found in species which had behaviour that required fast reaction times. For example, animals that fly and predators which pursue their prey, like yellowfin tuna which can swim at over 70 kmph earning them the nickname of cheetah of the sea.
In contrast, the slowest rates of temporal perception were found in slower-moving species, such as the crown-of-thorns starfish which clock a top speed of 22 meters per hour.
We also found that in aquatic environments smaller species had faster vision. For example, while a one gram threespined stickleback fish can see at 67 Hz, a 350kg Leatherback can only see at 15 Hz. This finding supports previous studies which tested the idea that smaller, more manoeuvrable animals would also have faster temporal perceptions.
Although it is still unknown why this relationship is particularly strong in aquatic environments, it may be because water allows for more instantaneous movement.
Not all environments or lifestyles encourage the evolution of faster eyes. Our analysis also found that species in dimmer environments had much lower temporal perception abilities. For example, the giant deep sea isopod (which looks a bit like a giant woodlouse) can only see at 4Hz and the nocturnal tokay gecko can only see at 21 Hz.
This lower temporal perception is due to the need to capture every photon, light particle, available in darker environments. Similar to using slower shutter speeds with a camera, eyes with retinal cells that fire more slowly are better adapted at capturing the faintest objects. However, such adaptations to the dark come at the expense of temporal perception, and like a wobbly night time photo, are susceptible to motion blur.
So what does a second feel like to a dragonfly or to a snail? As Thomas Nagel outlined in his 1974 philosophical essay, What Is It Like to Be a Bat, we can never subjectively understand what the temporal perception of a dragonfly or snail feels like. However, by measuring the limitations of their sensory system we can grasp some sense of it.
A cup falling to the floor, a car speeding past on the street or a series of lightning strikes – for us humans, an event on the scale of a second is typically a blur, something we can just about register but not in much detail. But animals all process a different amount of visual information in a second. To us, a dragonfly may seem like Neo in the Matrix experiencing bullet time, seeing the world in slow motion.
And the extremely slow temporal perception of starfish of snails means their experience or the world is probably limited to a series of blurs.
Hence while a second may be physically the same for every organism on Earth, how you perceive it depends on how fast you live.
Kevin Healy, Lecturer in Macroecology, University of Galway
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This article is republished from The Conversation under a Creative Commons license. Read the original article.
