Mice are nocturnal creatures, meaning they are usually asleep during the daytime and active at night. This can make them hard to detect; mice typically sneak around your house with ninja stealth and (unless you’re on the lookout for droppings) can go unnoticed for a long time.
Mice (and other species of rodents) are equipped with special adaptations that allow them to thrive in darkness. This allows them to hide away unnoticed in crawlspaces, walls, storage boxes, and furniture. Over time, a large number of rodents can accumulate, causing massive damage to the structure and contents of your house.
But how do rodents navigate their nighttime missions so well? Can mice see in the dark, or do they use other special skills to get around?
How well can mice see? Can they see in the dark?
Mice actually can’t see well in any lighting. Their vision is very poor in comparison to humans; so bad in fact that if they were people, they would be considered legally blind.
However, their eyes do have certain adaptations that help them survive in the dark. One study found that mouse eyes may be geared up to detect motion in dim light, giving them an edge over potential night-time predators.
But if their vision is generally so poor, how do they get around at night without constantly bumping into things?
How do mice use their whiskers to get around in the dark?
Nocturnal rodents, like rats and mice, have poor vision and must use other methods to get around and avoid predators in the dark. One special adaptation they have for doing this is their whiskers.
Rats and mice have rows of whiskers all the way along with their faces, and each one is controlled by a group of muscles that allow them to move around independently. At the base of each whisker is a follicle packed with mechanoreceptors (receptors that detect touch). These send signals back to the brain when the whiskers brush up against an object, telling the rodent exactly where and what that object is.
As they move around at night, mice repeatedly swish their whiskers back and forth. This behavior, known as whisking, allow the mouse to ‘feel’ around itself and detect nearby objects. In this way, mice and rats are able to navigate obstacles in the dark, without any need to use their eyes at all.
How do mice use their noses to get around in the dark?
Besides whisking, mice utilize another behavior to help them get around in the dark, and that’s sniffing. Rats and mice sniff constantly as they move around their environment, using their excellent sense of smell to find food, seek out mates and avoid predators.
And what about other rodents? Can rats see in the dark? Can squirrels?
Like mice, rats are primarily nocturnal creatures and spend most of their active time in the dark. Though they also have poor vision, like mice they equipped with special adaptations that allow them to thrive at night. By whisking and sniffing, they can navigate obstacles, find food and water and avoid nocturnal predators.
Diurnal rodents, like squirrels, are mainly active during the daytime. These animals are adapted to spending most of their waking hours in the daylight, and they have much better eyesight than rats and mice as a result. However, they are less skilled at using their other sense to get around in the dark. This is because, unlike rats and mice, they are usually asleep at night and have less need to find food and avoid predators after dark.
The future of sight: how scientists gave mice infrared vision so they could see in the dark
All mammals (including humans) can see a certain range of wavelengths that, collectively, are known as ‘visible light.’ This allows us to see a wide spectrum of color, but some wavelengths, such as infrared, are invisible to our eyes.
Infrared radiation is all around us and is mainly given off by heated objects. Objects can also reflect infrared radiation.
Thermal imaging and night vision technology both use infrared radiation to create visible images, allowing us to see in the dark. This technology has major applications in surveillance, photography, tracking and weather forecasting, among other fields.
At the beginning of 2019 scientists took infrared technology to the next level in a bid to push the limitations of our visible capabilities. Research published in February made the incredible find that, by injecting nanoparticles into mice eyes, scientists were able to give the mice infrared vision. This, essentially, allows them to see in the dark.
Once injected, the nanoparticles bound tightly to the cells in the mice eyes that detect light. Here, the nanoparticles captured infrared wavelengths and, at the same time, emitted shorter wavelengths. These shorter wavelengths fell within the ‘visible light’ range and could be detected by the mice eyes, producing a visible image.
If this technology were to be used in humans, we would be able to see in the dark. The images we’d see would appear green in color – just as if we were wearing built-in night vision goggles!
Rodents like rats and mice are primarily active at night, so can these creatures see in the dark? Although the vision of rats and mice is generally poor, their eyes are good at detecting motion in dim light, which can help them to avoid predators. What they lack in night vision they make up for with their other senses, and nocturnal rodents are adept at using their whiskers to ‘feel’ out their surrounding environment. They also have an excellent sense of smell, which they use to seek out food and mates while avoiding predators in the dark.