Cat senses are adaptations that allow cats to be highly efficient predators. Cats are good at detecting movement in low light, have an acute sense of hearing and smell, and their sense of touch is enhanced by long whiskers that protrude from their heads and bodies. These senses evolved to allow cats to hunt effectively at dawn and dusk.
Cats have a tapetum lucidum , which is a reflective layer behind the retina that sends light that passes through the retina back into the eye. [1] They also have a high number of rods in their retina that are sensitive to dim light. [2] While these improve the ability to see in darkness and enable cats to see using roughly one-sixth the amount of light that humans need, they appear to reduce net visual acuity, thus detracting when light is abundant. A cat's visual acuity is anywhere from 20/100 to 20/200, which means a cat has to be at 6 metres to see what an average human can see at 20 or 30 metres. Cats seem to be nearsighted, which means they cannot see far objects as well. The ability to see close objects would be well-suited for hunting and capturing prey. [2] In very bright light, the slit-like pupil closes very narrowly over the eye, reducing the amount of light on the sensitive retina, and improving depth of field. Big cats have pupils that contract to a round point. Variation in color of cats' eyes in flash photographs is largely due to the reflection of the flash by the tapetum.
Cats have a visual field of view of 200° compared with 180° in humans, but a binocular field (overlap in the images from each eye) narrower than that of humans. As with most predators, their eyes face forward, affording depth perception at the expense of field of view. Field of view is largely dependent upon the placement of the eyes, but may also be related to the eye's construction. Instead of the fovea, which gives humans sharp central vision, cats have a central band known as the visual streak. [3]
Common for carnivorans (and most mammals), cats are dichromats with two types of cone opsins, LWS (OPN1LW) and SWS1 (OPN1SW), somewhat similar to a human with protanopia. [4] Cats can see some colors and can tell the difference between red, blue and yellow lights, as well as between red and green lights. [5] Cats are able to distinguish between blues and violets better than between colors near the red end of the spectrum. But cats cannot see the same richness of hues and saturation of colors that humans can. [2] A 2014 study found that, along with several other mammals, cats lenses transmit significant amounts of ultraviolet (UVA 315–400 nm) light, which suggests that they possess sensitivity to this part of the spectrum. [6] [7]
Cats have a third eyelid, the nictitating membrane, which is a thin cover that quickly closes from the side when the cat blinks and is hidden when the cat's eyelid opens. [8] This third eyelid extends upward to protect the eye from trauma, like when moving through tall grass or capturing a prey. [8] This membrane partially closes if the cat is sick, although in a sleepy state this membrane is often visible. [9] [10]
Cats often sleep during the day and some periods of the night so they can hunt at dusk and dawn. Unlike humans, cats do not need to fully blink their eyes on a regular basis to keep their eyes lubricated (with tears). [8]
Cats have one of the broadest ranges of hearing among mammals. [11] Humans and cats have a similar range of hearing on the low end of the scale, but cats can hear much higher-pitched sounds, up to 64 kHz, which is 1.6 octaves above the range of a human, and 1 octave above the range of a dog. [12]
When listening for something, a cat's ears will swivel in that direction; a cat's ear flaps (pinnae) can independently point backwards as well as forwards and sideways to pinpoint the source of the sound. Cats can judge within 8 centimetres (3 inches) the location of a sound being made 1 metre (1 yard) away [13] —this can be useful for locating their prey.
It is a common misconception that all white cats with blue eyes are deaf. [14] This is not true, as there are many blue-eyed cats with perfect hearing. However, white cats with blue eyes do have slightly higher probability of genetic deafness than white cats of other eye colors. [15] White cats having one blue and one other-colored eye are called "odd-eyed" and may be deaf on the same side as the blue eye. [16] This is the result of the yellow iris pigmentation rising to the surface of only one eye, as blue eyes are normal at birth before the adult pigmentation has had a chance to express itself in the eye(s).
A domestic cat's sense of smell is 9-16 times as strong as humans'. [17] Cats have a larger olfactory epithelium than humans (about 20 cm2), meaning that cats have a more acute sense of smell. [18] In fact, cats have an estimated 45 to 200 million odor-sensitive cells in their noses, whereas humans only have 10 million odor-sensitive cells (known as "olfactory receptor neurons", or "ORNs"). [19] [20] [21] Cats also have a scent organ in the roof of their mouths called the vomeronasal (or Jacobson's) organ. When a cat wrinkles its muzzle, lowers its chin, and lets its tongue hang a bit, it is opening the passage to the vomeronasal. This is called gaping. It is equivalent to the Flehmen response in other animals, such as dogs, horses and big cats.
A cat has about twenty-four movable vibrissae ("whiskers"), in four sets on each upper lip on either side of its nose (some cats may have more). There are also a few on each cheek, tufts over the eyes, bristles on the chin, the cat's inner "wrists", and at the back of the legs. [22] The Sphynx (a nearly hairless breed) may have full length, short, or no whiskers at all. [23]
The structure of the brain region (barrel cortex) which receives information from the vibrissae is similar to that found in the visual cortex which permits the cat to create a three-dimensional map of its surroundings. This does not mean that sensing with vibrissae is a type of vision. It is still a touch sensation and environmental information is built up incrementally (in small steps). [24] [25] [26] [27]
Vibrissae aid sensation and navigation. The upper two rows of whiskers are able to be moved independently from the lower two rows for greater precision during measurement. A cat's whiskers are more than twice as thick as ordinary cat hairs, and their roots are three times deeper in a cat's tissue than other hairs. They have numerous nerve endings at their base, which give cats extraordinarily detailed information about nearby air movements and objects with which they make physical contact. They enable a cat to know that it is near obstacles without it needing to see them.
Whiskers also aid in hunting. High speed photography reveals that when a cat is unable to see its prey because it is too close to its mouth, its whiskers move so as to form a basket shape around its muzzle in order to precisely detect the prey's location. [28] [29] [ failed verification ] A cat whose whiskers have been damaged may bite the wrong part of its prey, indicating that they provide cats with detailed information about the shape and activity of its prey.
The cat family has specialized taste bud receptors. Positively, their taste buds possess the two receptors TAS1R1 and TAS1R3 needed to detect umami. These receptors contain molecular changes that reduce their detection of glutamic acid and aspartic acid, the main amino acids tasted as umami flavor in humans while enhancing their detection of the nucleotides inosine monophosphate and free l-Histidine. [30] These nucleotides are particularly enriched in tuna. [30] One of the researchers involved in this research has claimed, "I think umami is as important for cats as sweet is for humans". [31] In their research paper they specifically argue the sensitivity to histidine and inosine explains the palatability of tuna for cats: "the specific combination of the high IMP and free l-Histidine contents of tuna, which produces a strong umami taste synergy that is highly preferred by cats". [30] Negatively, cats lack the TAS1R2 protein, one of two required for function of the sweetness sensory receptor. This is due to a deletion in the relevant gene (Tas1r2) causes a shift in the genetic reading frame, leading to transcription stopping early and no detectable mRNA or protein produced. [32] The other protein, TAS1R3, is present and identical to that of other animals, and the relevant taste buds are still present but inactive. Such a genetic marker found in the entire family and not other animals must be the result of a mutation in an early ancestor; as a deletion mutation it could not revert, and thus would be inherited by all descendants, as the evolutionary tree branched out. Some scientists now believe this is the root of the cat family's extremely specialized evolutionary niche as a hunter and carnivore. Their modified sense of taste would cause them to some degree to ignore plants, a large part of whose taste appeal derives from their high sugar content, in favor of a high-protein carnivorous diet, which would still stimulate their remaining taste receptors.
The cat, commonly referred to as the domestic cat or house cat, is the only domesticated species in the family Felidae. Recent advances in archaeology and genetics have shown that the domestication of the cat occurred in the Near East around 7500 BC. It is commonly kept as a house pet and farm cat, but also ranges freely as a feral cat avoiding human contact. It is valued by humans for companionship and its ability to kill vermin. Because of its retractable claws, it is adapted to killing small prey like mice and rats. It has a strong, flexible body, quick reflexes, sharp teeth, and its night vision and sense of smell are well developed. It is a social species, but a solitary hunter and a crepuscular predator. Cat communication includes vocalizations like meowing, purring, trilling, hissing, growling, and grunting as well as cat body language. It can hear sounds too faint or too high in frequency for human ears, such as those made by small mammals. It also secretes and perceives pheromones.
Felidae is the family of mammals in the order Carnivora colloquially referred to as cats. A member of this family is also called a felid. The term "cat" refers both to felids in general and specifically to the domestic cat.
An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system.
Night vision is the ability to see in low-light conditions, either naturally with scotopic vision or through a night-vision device. Night vision requires both sufficient spectral range and sufficient intensity range. Humans have poor night vision compared to many animals such as cats, dogs, foxes and rabbits, in part because the human eye lacks a tapetum lucidum, tissue behind the retina that reflects light back through the retina thus increasing the light available to the photoreceptors.
The tapetum lucidum 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 the light available to the photoreceptors. The tapetum lucidum contributes to the superior night vision of some animals. Many of these animals are nocturnal, especially carnivores, while others are deep sea animals.
Whiskers or vibrissae are a type of stiff, functional hair used by most mammals to sense their environment. These hairs are finely specialised for this purpose, whereas other types of hair are coarser as tactile sensors. Although whiskers are specifically those found around the face, vibrissae are known to grow in clusters at various places around the body. Most mammals have them, including all non-human primates and especially nocturnal mammals.
The sensory nervous system is a part of the nervous system responsible for processing sensory information. A sensory system consists of sensory neurons, neural pathways, and parts of the brain involved in sensory perception and interoception. Commonly recognized sensory systems are those for vision, hearing, touch, taste, smell, balance and visceral sensation. Sense organs are transducers that convert data from the outer physical world to the realm of the mind where people interpret the information, creating their perception of the world around them.
In visual physiology, adaptation is the ability of the retina of the eye to adjust to various levels of light. Natural night vision, or scotopic vision, is the ability to see under low-light conditions. In humans, rod cells are exclusively responsible for night vision as cone cells are only able to function at higher illumination levels. Night vision is of lower quality than day vision because it is limited in resolution and colors cannot be discerned; only shades of gray are seen. In order for humans to transition from day to night vision they must undergo a dark adaptation period of up to two hours in which each eye adjusts from a high to a low luminescence "setting", increasing sensitivity hugely, by many orders of magnitude. This adaptation period is different between rod and cone cells and results from the regeneration of photopigments to increase retinal sensitivity. Light adaptation, in contrast, works very quickly, within seconds.
Stimulus modality, also called sensory modality, is one aspect of a stimulus or what is perceived after a stimulus. For example, the temperature modality is registered after heat or cold stimulate a receptor. Some sensory modalities include: light, sound, temperature, taste, pressure, and smell. The type and location of the sensory receptor activated by the stimulus plays the primary role in coding the sensation. All sensory modalities work together to heighten stimuli sensation when necessary.
In medicine and anatomy, the special senses are the senses that have specialized organs devoted to them:
Dog anatomy comprises the anatomical studies of the visible parts of the body of a domestic dog. Details of structures vary tremendously from breed to breed, more than in any other animal species, wild or domesticated, as dogs are highly variable in height and weight. The smallest known adult dog was a Yorkshire Terrier that stood only 6.3 cm (2.5 in) at the shoulder, 9.5 cm (3.7 in) in length along the head and body, and weighed only 113 grams (4.0 oz). The heaviest dog was an English Mastiff named Zorba which weighed 314 pounds (142 kg). The tallest known adult dog is a Great Dane that stands 106.7 cm (42.0 in) at the shoulder.
A taste receptor or tastant is a type of cellular receptor which facilitates the sensation of taste. When food or other substances enter the mouth, molecules interact with saliva and are bound to taste receptors in the oral cavity and other locations. Molecules which give a sensation of taste are considered "sapid".
The equine eye is one of the largest of any land mammal. Its visual abilities are directly related to the animal's behavior; for example, it is active during both day and night, and it is a prey animal. Both the strengths and weaknesses of the horse's visual abilities should be taken into consideration when training the animal, as an understanding of the horse's eye can help to discover why the animal behaves the way it does in various situations.
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". Birds are theropod dinosaurs, and the avian eye resembles that of other reptiles, with ciliary muscles that can change the shape of the lens rapidly and to a greater extent than in the mammals. Birds have the largest eyes relative to their size in the animal kingdom, and movement is consequently limited within the eye's bony socket. In addition to the two eyelids usually found in vertebrates, bird's eyes are protected by a third transparent movable membrane. The eye's internal anatomy is similar to that of other vertebrates, but has a structure, the pecten oculi, unique to birds.
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 possessing a trichromatic color perception.
Visual perception in animals plays an important role in the animal kingdom, most importantly for the identification of food sources and avoidance of predators. For this reason, blindness in animals is a unique topic of study.
A sense is a biological system used by an organism for sensation, the process of gathering information about the surroundings through the detection of stimuli. Although, in some cultures, five human senses were traditionally identified as such, many more are now recognized. Senses used by non-human organisms are even greater in variety and number. During sensation, sense organs collect various stimuli for transduction, meaning transformation into a form that can be understood by the brain. Sensation and perception are fundamental to nearly every aspect of an organism's cognition, behavior and thought.
Vision is an important sensory system for most species of fish. Fish eyes are similar to the eyes of terrestrial vertebrates like birds and mammals, but have a more spherical lens. Birds and mammals normally adjust focus by changing the shape of their lens, but fish normally adjust focus by moving the lens closer to or further from the retina. Fish retinas generally have both rod cells and cone cells, and most species have colour vision. Some fish can see ultraviolet and some are sensitive to polarised light.
In animal physiology, hydrodynamic reception refers to the ability of some animals to sense water movements generated by biotic or abiotic sources. This form of mechanoreception is useful for orientation, hunting, predator avoidance, and schooling. Frequent encounters with conditions of low visibility can prevent vision from being a reliable information source for navigation and sensing objects or organisms in the environment. Sensing water movements is one resolution to this problem.
The eagle eye is among the sharpest in the animal kingdom, with an eyesight estimated at 4 to 8 times stronger than that of the average human. Although an eagle may only weigh 10 pounds (4.5 kg), its eyes are roughly the same size as those of a human. Eagle weight varies: a small eagle could weigh 700 grams (1.5 lb), while a larger one could weigh 6.5 kilograms (14 lb); an eagle of about 10 kilograms (22 lb) weight could have eyes as big as that of a human who weighs 200 pounds (91 kg). Although the size of the eagle eye is about the same as that of a human being, the back side shape of the eagle eye is flatter. Their eyes are stated to be larger in size than their brain, by weight. Color vision with resolution and clarity are the most prominent features of eagles' eyes, hence sharp-sighted people are sometimes referred to as "eagle-eyed". Eagles can identify five distinctly colored squirrels and locate their prey even if hidden.
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