Posted on 11/08/2007 7:09:03 PM PST by blam
How Well Do Dogs See At Night?
ScienceDaily (Nov. 9, 2007) — A lot better than we do, says Paul Miller, clinical professor of comparative ophthalmology at University of Wisconsin-Madison.
Dogs have good night vision, due in large part to the tapetum, a mirror-like structure which reflects light, giving the retina a second chance to register light that has entered the eye. This is also what makes dogs eyes glow at night. The dog is holding a toy in her mouth. (Credit: Michele Hogan)
“Dogs have evolved to see well in both bright and dim light, whereas humans do best in bright light. No one is quite sure how much better a dog sees in dim light, but I would suspect that dogs are not quite as good as cats,” which can see in light that’s six times dimmer than our lower limit. Dogs, he says, “can probably see in light five times dimmer than a human can see in.”
Dogs have many adaptations for low-light vision, Miller says. A larger pupil lets in more light. The center of the retina has more of the light-sensitive cells (rods), which work better in dim light than the color-detecting cones. The light-sensitive compounds in the retina respond to lower light levels. And the lens is located closer to the retina, making the image on the retina brighter.
But the canine’s biggest advantage is called the tapetum. This mirror-like structure in the back of the eye reflects light, giving the retina a second chance to register light that has entered the eye. “Although the tapetum improves vision in dim light, it also scatters some light, degrading the dog’s vision from the 20:20 that you and I normally see to about 20:80,” Miller says.
The tapetum also causes dog eyes to glow at night.
Adapted from materials provided by University of Wisconsin - Madison.
My poor dog is developing cataracks and not seeing less and less.
She’s a b..ch???
Oops! seeing less and less.
My oldest one is doing the same.
I know this doesn’t belong here but all you 50 and 60 boomers you are in for a treat.
It’s Ray Charles, Jerry Lee Lewis and Fats Domino playing the piano together.
http://www.dailymotion.com/video/xe5w0_ray-charles-jerry-lee-lewis
Goa’uld
Thank God. It's the only way I can find my chocolate lab in a dark yard at night using a flashlight.
Same with my Yellow Lab. His eyes glow golden yellow!
On average men see better at night than women. Women are more sensitive to color than men. It’s all in the rods and cones!!
Question: Turtles have all-cone vision---what for?
Here's a treat.
It’s Ray Charles, Jerry Lee Lewis and Fats Domino playing the piano together.
All I can Say is WOW!!!!!
My black poodle disappears in the shadows also.
PetsMart has a fiber optic-like collar powered by a button battery. Works great.
We have used a lighted arm band available at Lowe's . They have a greenish reflective coating and are battery powered glowing also. Continuous or flashing.
Either are about $10.
My neighbors little dog has green eyes. The dog looks freaky when the light hits her eyes right. I call the dog “My Little Martian”.
Is it possible to have a thread on any subject without injecting Hillary ..... please?????
Albert Payson Terhune said the same thing 80 + years ago.
I haven’t heard that in years. Thank you.
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