In the spirit of Halloween, here are some animals with glowing, demonic eyes. The eyes of nocturnal animals brightly reflect various colors of light in flash photography due to the presence of a special layer behind the retina, the tapetum lucidum, that reflects light back into the retina to improve their vision in low light conditions.

Humans do not have a tapetum lucidum and instead light reaches the blood-rich region at the back of the eye and is reflected back through the eye as red-eye. Unlike the brightly shining eyes of nocturnal animals, which are visible by flashlight or car headlights, human red-eye is only visible in close flash photography.

This Chesapeake Bay Retriever's eyes reflect green, which is a very common eye shine color in dogs.

Despite her glowing eyes, this dog is anything but demonic. Her name is Angel and she likes to smile (submissive grin) at me when she greets me. Chesapeake Bay Retrievers are an American breed, and they are the largest, strongest, and most aggressive type of retriever. These dogs are very tough and excel at retrieving ducks in waters too cold or difficult for other retrievers. Chesapeake Bay Retrievers make excellent, steady watch dogs and loyal companions. They are a calm, but stubborn breed and require a dominant owner. Chesapeake Bay Retrievers are very intelligent and have a particular affinity for language, and not only will they easily learn human words, many of them will also growl-talk back to you as well.

Another common eye shine color in dogs is yellow, as can be seen by these golden eyes in the adorable face of an Airedale Terrier.

This dog's name is Sara and she is a real sweetheart with the face of a teddy bear. Airedale Terriers are good watchdogs and can be protective, but Sara is a very nice, friendly dog. She likes to sit in your lap because even though she's a big, adult dog, she thinks that she's still just a small baby. Airedale Terriers are very trainable, and these happy, lively dogs like to be kept active.

Less common are adult dogs with blue eye shine like this Doberman Pinscher.

This Doberman's name is Chablis and she is very loving and submissive to people she knows, but rather suspicious of strangers. Dobermans have the most lovely, smooth coats and they are a true delight to stroke, which is fortunate because Chablis is one of the most affectionate dogs I have ever known. She will happily nuzzle and nibble on my neck as I stroke the satiny fur on her head and neck. I think that she views it as friendly mutual grooming as if I was another dog. Unlike Chablis, my dog Bounder, who is only half Doberman, has green eye shine.

Animals with red eye shine are Great Horned Owls as well as their favorite prey, rabbits like this Desert Cottontail (Sylvilagus auduboni).

I have several semi-tame Desert Cottontails visiting my bird pond and showing up every morning for a scattering of birdseed. I like to see them playing tag and scampering about down in my driveway late in the day before the feared Great Horned Owls emerge.