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The dark blue, teal, and gold tapetum lucidum from the eye of a cow Retina of a mongrel dog with strong tapetal reflex. The tapetum lucidum (Latin for 'bright tapestry, coverlet'; / t ə ˈ p iː t əm ˈ l uː s ɪ d əm / tə-PEE-təm LOO-sih-dəm; pl.: tapeta lucida) [1] is a layer of tissue in the eye of many vertebrates and some other animals.
The human eye, showing the iris and pupil. In 1802, philosopher William Paley called it a miracle of "design."In 1859, Charles Darwin himself wrote in his Origin of Species, that the evolution of the eye by natural selection seemed at first glance "absurd in the highest possible degree". [3]
They have difficulty differentiating between red and green, [40] and much like other mammals, the dog's eye is composed of two types of cone cells compared to the human's three. The divergence of the eye axis of dogs ranges from 12 to 25°, depending on the breed, which can have different retina configurations.
The head is well balanced in proportion to the size of the dog and is deeper than broad with the length of muzzle and the length of skull roughly equal. With close-fitting eyelids, the eyes are set into the skull upon a slight oblique; the eyes are medium-sized, almond-shaped, and colored dark brown.
Dingo on the beach at Fraser Island, Queensland. The dingo (either included in the species Canis familiaris, or considered one of the following independent taxa: Canis familiaris dingo, Canis dingo, or Canis lupus dingo) is an ancient lineage of dog [5] [6] found in Australia.
Dogs may be entering a new wave of evolution as humans’ need for companionship grows. Image credits: Jamie Street / Unsplash. A study concluded that oxytocin is the “love” hormone that ...
Cherry eye in dogs can be a concerning condition as it can look very angry and uncomfortable. Many animals have three sets of eyelids (so do humans, but ours are much smaller) and the tear gland ...
There is an extensive list of genes showing signatures of parallel evolution in dogs and humans. This has led to the study of the coevolution of gene function. 311 genes under positive selection in dogs are related to a large number of overlapping loci which show the same patterns in humans.