Several animals exhibit green, glowing eyes at night due to a reflective layer behind their retina called the tapetum lucidum.
Animals with Green Eyeshine
Based on available information, foxes, domestic cats, and dogs commonly display green eyeshine at night. This glowing effect occurs when light enters the eye and is reflected back out by the tapetum lucidum, enhancing night vision.
However, it's important to note that the color of eyeshine can vary. While green is typical for these animals, cats, in particular, can also have eyeshine that ranges from orange to red.
Factors Influencing Eyeshine Color
The color of the eyeshine isn't fixed and can depend on several factors:
- Species: Different species often have different predominant eyeshine colors.
- Breed: Within a species, breed can influence the color.
- Individual Variation: Even within the same breed, there can be variation.
- Chemical Composition: As seen in domestic cats, variations in the amounts of substances like zinc or riboflavin within the tapetum lucidum can affect the resulting eyeshine color.
- Angle of Light: The angle at which light reflects off the tapetum lucidum can also sometimes appear to change the color perceived by an observer.
Common Eyeshine Colors by Animal (Based on Reference)
Here's a summary based on the provided reference:
| Animal | Usual Eyeshine Color(s) | Notes |
|---|---|---|
| Fox | Green | Typically green |
| Domestic Cat | Green, Orange, Red | Can vary widely |
| Domestic Dog | Green | Typically green, can vary by breed |
Understanding Eyeshine
The glowing effect isn't the animal's eyes producing light; rather, it's reflected light. When a light source, like a flashlight or headlights, hits the animal's eye, the tapetum lucidum bounces the light back through the retina, giving the photoreceptor cells a second chance to capture the light. This significantly improves their ability to see in low-light conditions. The color we see is determined by the specific compounds and structure of this reflective layer.
While many animals possess a tapetum lucidum, the visible color of the eyeshine can range across the spectrum, including blue, yellow, and white, in addition to green, orange, and red.
