With their beady eyes and nocturnal nature, you may wonder if possums have good eyesight. As a marsupial that is most active at night, the possum has evolved some unique adaptations to help it see in the dark.
If you’re short on time, here’s a quick answer to your question: Possums do not have particularly good eyesight compared to humans. Their vision is adapted for low light conditions, but they rely more heavily on their senses of smell and hearing.
In this approximately 3000 word article, we’ll take an in-depth look at possum eyes, their night vision capabilities, how their eyes compare to other animals, and more. We’ll also bust some myths about their eyesight and vision abilities.
Keep reading to learn all about the possum’s unique eyes and visual system.
Anatomy of the Possum Eye
Size and Placement
Possums have relatively large eyes compared to the size of their head. Their eyes are set more to the sides of their face, giving them a wide field of monocular vision on either side. This aids possums in detecting predators while foraging at night.
Tapetum Lucidum
One of the most unique features of the possum eye is the tapetum lucidum. This is a reflective layer behind the retina that acts like a mirror, bouncing light back through the retina to give photoreceptors a second chance to detect the image.
This allows possums to see much better in low light conditions, a great adaptation for a nocturnal mammal.
Research has shown the possum tapetum lucidum reflects blue and green light most strongly. This is likely an evolutionary adaptation to seeing at night, as these wavelengths are most abundant in moonlight.
Rod-Dominated Retina
The possum retina is dominated by rod photoreceptor cells, which are extremely sensitive to low light. Possums have around 20 times more rods than cones in their retina. The high proportion of rods allows them to see well in dim conditions, with enough light for the highly sensitive rods but not enough for the less sensitive cones.
While excellent for night vision, the lack of cones results in poor color vision. Possums can distinguish some colors, but their world is mostly shades of grey when the sun goes down.
Possum Vision Capabilities
Enhanced Night Vision
Possums have excellent night vision compared to many other mammals. Their eyes contain a special membrane called the tapetum lucidum that reflects light back through the retina, allowing more light absorption in low light conditions.
This gives them superior vision at night to navigate and hunt for food under darkness.
Poor Daytime Vision
While highly adapted for low light, possums have rather poor vision during daytime. Their pupils do not contract enough in brighter light, overwhelming their retinas used to night vision. As crepuscular animals most active dawn and dusk, they rely less on daytime vision.
Motion Detection
Their eyes are specially tuned for detecting motion in low light. Possums have high densities of rod photoreceptor cells which are more sensitive to movement, and more optic nerve connections dedicated to night vision. This aids their ability to spot prey and threats active in darkness.
Limited Color Vision
In addition to more rod cells for low light sensitivity, possums have far less cone cells for color vision. They can likely see some color, but their world view is dominated by shades of gray rather than a full color spectrum.
As nocturnal marsupials, vivid color vision is less essential to their niche.
Comparison to Other Animals
Vs. Humans
Unlike humans who have excellent eyesight and color vision, possums have rather poor vision. Their eyes are smaller relative to their body size. Research suggests the acuity and light sensitivity of possum eyes is 5-10 times lower than that of humans.
While humans have a visual field spanning nearly 180 degrees horizontally, the possum’s visual field only spans around 135 degrees. Their binocular vision where both eyes focus on a single object is also more limited at around 50 degrees compared to humans’ 140 degrees.
But what possums lack in visual detail and color perception, they make up for in excellent night vision and ability to detect movement. Their eyes have abundant rod photoreceptors but few cone photoreceptors, perfectly adapted for nocturnal activity.
Vs. Cats
Research has found possum eyesight to be inferior even compared to cats. Possums score much lower in visual acuity tests. While cats have excellent night vision rivaling owls and can see some color, possums struggle to identify fine details, shapes and color variations under low light conditions where cats excel.
| Animal | Visual Acuity Estimate |
|---|---|
| Cat | Around 9 cycles/degree |
| Possum | Around 2 cycles/degree |
But possums tend to have a wider field of view than cats, allowing them to more easily detect danger from the periphery. Their pupils also dilate wider in the dark to maximize light intake.
Vs. Other Marsupials
Research comparing the vision of the brushtail possum to other marsupials reveals some similarities but also key differences. Like most marsupials, possums are adapted for low light vision with abundant night vision receptors.
But tests of their visual acuity, light sensitivity threshold, and ability to distinguish colors shows the brushtail ranks behind other marsupials like kangaroos and wallabies. Scientists believe this may be linked to the brushtail’s more solitary and nighttime lifestyle.
Common Myths and Misconceptions
Playing Possum and Eyes
One common myth is that possums play dead with their eyes open. While possums do go into a catatonic state when threatened, called “playing possum”, their eyes actually remain closed. This likely helps them appear convincingly dead to potential predators.
However, some witnesses may incorrectly remember the possum’s eyes being open when it was playing dead, leading to this misconception.
Blindness
Another myth is that possums are blind or have very poor eyesight. This likely stems from their small, bead-like eyes and nocturnal nature. However, possums can actually see quite well in low light conditions. Their eyes have a high density of rod cells, which aid night vision.
While their daytime vision is limited, possums are not blind and rely heavily on their eyesight when active at night.
Eyes Glowing in the Dark
Many have claimed to see possum eyes glowing eerily in the dark. This myth likely arose because possums’ eyes reflect light well. The light-reflecting tapetum lucidum behind their retinas amplifies dim light. This helps them see at night but can also produce eyeshine when illuminated.
So while their eyes don’t produce light, they do sometimes appear to glow brightly in the dark when light shines on them.
Conclusion
While possums may have a bit of a reputation for poor eyesight, their vision is actually well-adapted for their nocturnal lifestyle. Their eyes maximize light capture with anatomical features like the tapetum lucidum. Possums can see well at night, though their daytime vision is quite poor.
Compared to humans and some other animals, possums prioritize detecting motion and seeing in low light over visual acuity. Their eyes strike the right balance for their needs as nocturnal hunters and foragers.
So next time you spot a possum’s eyes glinting in the beam of a flashlight or glowing slightly in your headlights, know that you’re seeing the light bounce off its tapetum lucidum, allowing it to make the most of the available light.
The possum’s unique eyes aren’t poor – they’re optimized for the possum’s lifestyle and needs.
