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Vision is the most important sense for birds, since good eyesight is essential for safe flight. Birds have a number of adaptations which give visual acuity superior to that of other vertebrate groups; a pigeon has been described as "two eyes with wings". [ 1] Birds are theropod dinosaurs, [ 2][ 3] and the avian eye resembles that of other ...
retina. Mammals normally have a pair of eyes. Although mammalian vision is not so excellent as bird vision, it is at least dichromatic for most of mammalian species, with certain families (such as Hominidae) possessing a trichromatic color perception. The dimensions of the eyeball vary only 1–2 mm among humans.
Mammalian vision. Mammalian vision is the process of mammals perceiving light, analyzing it and forming subjective sensations, on the basis of which the animal's idea of the spatial structure of the external world is formed. Responsible for this process in mammals is the visual sensory system, the foundations of which were formed at an early ...
A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, [ 1] which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distinguish brightness and color. The image perceived by this arthropod eye is a combination of inputs ...
The anatomy of bird's respiratory system, showing the relationships of the trachea, primary and intra-pulmonary bronchi, the dorso- and ventro-bronchi, with the parabronchi running between the two. The posterior and anterior air sacs are also indicated, but not to scale. Inhalation–exhalation cycle in birds.
Parietal eye. A parietal eye ( third eye, pineal eye) is a part of the epithalamus in some vertebrates. The eye is at the top of the head; is photoreceptive; and is associated with the pineal gland, which regulates circadian rhythmicity and hormone production for thermoregulation. [ 1] The hole that contains the eye is known as the pineal ...
The tapetum lucidum ( Latin for 'bright tapestry, coverlet'; / təˈpiːtəm ˈluːsɪdəm / 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. Lying immediately behind the retina, it is a retroreflector. It reflects visible light back through the retina, increasing ...
Fish retinas generally have both rod cells and cone cells (for scotopic and photopic vision ), and most species have colour vision. Some fish can see ultraviolet and some are sensitive to polarised light . Among jawless fishes, the lamprey [1] has well-developed eyes, while the hagfish has only primitive eyespots. [2]