Understanding Cat Sensory Abilities

Title: URL Source: blob://pdf/b5229e63-188f-4b5f-a8c4-e4a8c6a21b7a Markdown Content: > 14 T. Atkinson, 2018. Practical Feline Behaviour (T. Atkinson) # 2 The Senses Because pet cats share our lives and our homes it can be easy to assume that their experience and perception of surrounding stimuli is the same as ours. But their sen-sory abilities, which have not changed from their wild ancestry, enable them to see, hear and smell things of which our senses leave us completely unaware. In a few respects, however, our senses are slightly better or at least just dissimilar but the over-all effect is that the cats view of the world is quite different to our own. # Sight Night vision There are a number of ways in which a domestic cats vision differs from human eyesight. The most well-known of these is the cats ability to see in the dark. In truth cats cannot see any better than we can in complete darkness but in low light conditions specific struc-tures of the feline eye allow them to utilize any available light far better than we can. The retina of mammalian eyes contains two types of photoreceptors: rods and cones. Cones function best in bright light and are responsible for colour vision. Rods are more light sensitive and function better in reduced light to allow vision in low-light conditions. A cats retina contains far more rods than cones, with the total number of rods being around three times greater than is found in the human eye (Steinberg et al ., 1973). The rod photoreceptor cells are not connected to fibres in the optic nerve individ-ually but are joined together in bundles, so that more visual receptors are con-nected to each nerve cell, resulting in even greater light detection. The disadvantage of this, however, is that it also reduces the clarity of the image (Miller, 2001). Cats have very large eyes in relation to body size. At 22 mm in diameter, they are only slightly smaller than human eyes, which are 25 mm. The large size of the eyes along with elliptical pupils allow for pupil dilation that is at least three times greater than our own, enabling a large amount of light to enter the eyes when required. In bright light the elliptical pupil can be reduced by constriction of the iris to a very small vertical slit only 1 mm wide to protect the retina from damage. (Fig. 2.1). A layer of reflective cells behind the retina called the tapetum lucidum more specifically the tapetum cellulosum in cats and some other carnivores reflects light that has not yet been absorbed by the photoreceptor cells back into the eye to allow another chance for absorption. This increases the efficiency of the eye in low light conditions by up to 40% (Bradshaw et al ., 2012). The tapetum is responsible for the characteristic reflective shine whenever a light is shone into a cats eyes. Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions The Senses 15 Movement detection Rapid eye movements known as saccades prevent moving images from blurring and enable cats to detect and accurately track fast movements, even if the movement is slight or to the side of the cats direct line of vision. Sensory information regarding the distance and angle of the object is sent to the muscles surrounding the lens (the ciliary muscles) but, if this calculation is incorrect or if the object moves in an unex-pected way, a second corrective saccade follows the first to get the line of vision back on target. This corrective imaging can occur around 60 times per second, at least twice as fast as we are capable of (Bradshaw et al ., 2012). Slow movements, however, are not so well detected. Humans can detect move-ments that are ten times slower than those that can be seen by cats (Pasternak and Merigan, 1980). Visual focusing Visual focusing is one way in which our eyes perform much better than those of cats. In human eyes, the lens is flexible and, depending on the overall health of the eye, is able to focus fairly accurately by distortion of the lens. But the lens within a cats eye is inflexible and focuses by moving backward and forward rather than distorting. The result is that cats are a little slower at transferring their visual focus from near to distance and vice versa and are unable to focus clearly on anything that is less than 25 cm away from their face. Colour vision Perception of colour is another way that human vision is superior. Humans have three types of colour sensitive cone photoreceptors (red, blue and yellow) and 16 times more colour-comparing nerves than cats, which allow us to see a far wider range of different colours. Rod photoreceptors only allow for monochromatic vision and it was once thought that cats can only see in black and white. But neurophysiological evidence > Fig. 2.1. Elliptical pupils can dilate more than round pupils, allowing more light to enter the eye. They can also constrict to very narrow slits to avoid damage to the retina from bright light. Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions 16 Chapter 2 shows that they possess two types of colour-sensitive cones that respond to light within the blue and green light spectrum, which means that they are likely to see yellow and blue as primary colours and their combination colours (Loop et al ., 1987). Behavioural research indicates, however, that cats colour perception may be muted or that they are behaviourally colour blind because they seem much more able to distinguish between differences in shape, pattern and brightness than between colours (Bradshaw et al ., 2012). Binocular vision Like us, cats have forward facing eyes that work together giving them stereoscopic or 3D vision (DeAngelis, 2000). This is achieved by each eye focusing on the same visual target and producing its own 2D image. These images overlap with each other result-ing in 3D vision. Stereoscopic vision is a great advantage for a predator because it allows for accurate judgment of depth and distance. Some Siamese cats have a genetic misrouting of retinal ganglion cells resulting in an inability to develop full stereoscopic vision (Bacon et al ., 1999). However, other than the development of an adaptational squint or cross-eyes, these cats appear otherwise unaffected and many are perfectly able to hunt successfully. Cross-eyed Siamese were quite common at one time, but are not seen so often now as more breeders have become aware of the genetic influence and choose not to breed from affected cats. Field of vision The field of vison is the area that can be seen when the eyes are fixed in one position. It is made up of the binocular visual field, where the two eyes work together to pro-vide a stereoscopic image, and the peripheral field which is outside of the central gaze and is non-binocular. Cats have about the same binocular field of vision as humans, about 90100. But their lateral peripheral visual field is wider, giving them a total of around 200 compared to around 180 in humans. # Hearing Cats have one of the widest ranges of hearing among mammals, extending from 48 Hz to 85 kHz (Heffner and Heffner, 1985), although it is generally accepted that the useful upper limit is more likely to be around 60 kHz because sounds above this frequency would have to be fairly loud for a cat to be able to hear them (Bradshaw et al ., 2012). Even so, it is still quite exceptional when you consider that the average human hearing range is approximately 20 Hz to 20 kHz. The hearing range of most mammals encompasses that necessary to hear species-specific auditory communications plus, if a predatory species, the sounds made by prey. Hearing is one of the cats main methods of prey detection; it is therefore not surprising that their hearing range enables them to hear the very high-pitched ultra-sound signalling made by small rodents and other small prey species. But their hearing Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions The Senses 17 range also encompasses much lower frequency sounds than would be expected. This can be a particular advantage for pet cats because it allows them to hear the full range of human speech, even the low-pitched human male voice. Cats also have very sensi-tive hearing, allowing them to hear not just the vocalizations but also the movements of small animals and insects. Their ability to detect minor differences in pitch and intensity between sounds is, however, inferior to our own and they are less able to detect sounds of very short duration. Our increased ability in this respect might be due to our need to detect such small changes in sound that occur in human language (Bradshaw, 2013). The pinna (the external part of the ear) plays a very important role in both the location of sounds and as a directional amplifier. Individual muscles allow each pinna to be moved independently and these movements can be both rapid and precise ena-bling the cat to accurately pinpoint the source of a sound. # Olfaction (Sense of Smell) Olfaction is an extremely important sense for cats because it is used in communica-tion, reproduction, feeding and hunting. It is therefore not surprising that cats have a highly sensitive and discriminative sense of smell. Olfactory receptor cells, which have a direct neural connection to the olfactory bulb in the brain, are found in the olfactory epithelium the lining of the nasal cav-ities. In humans this covers an area of around 25 cm 2 and contains around 5 million receptors. In cats the olfactory epithelium is supported by the scroll-like nasal turbinate bones, the ethmoturbinals, and covers a total surface area of approxi-mately 2040 cm 2 , containing around 200 million receptors (Ley, 2016). These are receptors of not just one type, but several hundred different types, enabling the cat to distinguish between an incredibly enormous number of different odours (Bradshaw et al ., 2012). The vomeronasal organ The vomeronasal organ, also known as the Jacobsons organ, is an additional olfac-tory organ found in many mammals but not in humans or other higher primates. It provides the animal with a sense that is probably something between taste and smell and appears to be used primarily to detect and identify pheromones used in intra-species communication (see Chapter 3). It consists of two blind-ended fluid-filled sacs, situated within the hard palate, that contain around 30 different types of chemical receptors. Scent is actively taken in through the mouth and towards the vomeronasal organ via two small slits, known as the nasopalatine ducts, positioned just behind the upper incisors. When utilizing the vomeronasal organ, a cat will exhibit a slightly odd facial expression or grimace whereby the mouth is held slightly open with the upper lip raised (Fig. 2.2). This is also known as the flehmen response, from the German verb meaning to bare the upper teeth. Flehmen is a voluntary behaviour and it is possible that the presence of other visual or olfactory signals, such as the scent of urine, might trigger this reaction (Mills et al ., 2013). Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions 18 Chapter 2 # Touch The vibrissae (whiskers) These are: The mystacials: the large whiskers on either side of the nose. The supercilliary: situated just above the eyes The genals: smaller hairs situated on the side of the face. Carpel hairs: found on the back of the forelegs. The whiskers, scientifically known as the vibrissae, are thickened hairs embedded deeply within the skin, around three times deeper than regular guard hairs. Large num-bers of mechanoreceptors, sensory neurons responsive to pressure or distortion, are found at the base of the vibrissae, making them sensitive enough to detect air currents. When the cat is hunting, the large facial whiskers (the mystacials) take over from the eyes to compensate for the cats poor close visual focusing. This is achieved by the whiskers being pushed forward to envelope the prey when it is close to the face enabling the cat to accurately detect and manipulate it. Cats are also able to get the best overall picture of their close surroundings and position in relation to nearby obstacles by com-bining visual input with sensory information from the whiskers (Bradshaw et al ., 2012). The feet A cats feet play an important role in hunting and defence, and are used to investigate and explore novel objects by touch. They are highly sensitive, containing a very high Fig. 2.2. The flehmen response, activating the vomeronasal organ. Lucy Hoile. Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions The Senses 19 density of mechanoreceptors both in and between the pads and in the soft tissue at the base of the claws. Specialist mechanoreceptors known as Pacinian or Lamellar corpuscles in the deeper skin layers also allow cats to detect vibrations through the pads of the feet (Verrillo, 1966). # Balance The vestibular system The vestibular system is the part of the inner ear responsible for the sense of balance in mammals. It is made up of the semicircular canals, and the saccular and utricular otolith organs. The semicircular canals are three fluid-filled tubes that also contain motion- sensitive hairs (cilia). They are: The Horizontal : which detects turns to the left or right. The Anterior and Posterior : which detect up and down movement and move-ments such as putting the head to one side. As the animal moves its head the vestibular system moves along with it but the fluid within the semicircular canals stays in place, thereby moving the hairs within the canals. The information about the movement is then relayed to the brain. The saccular and utricular otolith organs also have cilia covering their internal surface, but rather than fluid these organs have tiny calcite crystals covering the sen-sory surface that brush against the hairs as the animal moves its head. The otolith organs detect acceleration, deceleration and gravity, allowing the animal to know when and how fast it is moving, and when it is the right way up. Although this is the same system as in other mammals, including humans, the cats semicircular canals are much nearer to being at right angles to each other than in many other mammals and the horizontal canal is more parallel to the normal head position. This allows the information detected by the cilia within the canals and relayed to the brain to be particularly clear and precise. Plus, the utricular otoliths, and possibly the saccular, are much better attuned to measure gravitational deviations (Bradshaw et al ., 2012). The Righting reflex The righting reflex, sometimes called the air-righting reflex is the cats ability to land on its feet from a fall. When a cat starts to fall the movement is instantly detected by the vestibular system and within one tenth of a second the head starts to turn towards the ground, allowing the cat to see where it will land. The highly flexible spine allows the body to then twist, front end first and then the back end so that the cat is facing the ground. Lastly, as the cat is about the land, the back arches and the legs extend ready to act as shock absorbers (Fig. 2.3). If the fall is from a considerable height the legs are initially pushed out sideways and only extended downwards as the cat is just about to land. This has the effect of reducing the falling speed and probably accounts for reports of cats surviving falls Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions 20 Chapter 2 from tall buildings with only minor injuries. But this does not always prevent cats from sustaining serious injury as it can also depend on the nature of the surface on which the cat lands. Injuries can also occur if the distance that the cat falls is too short. Although the righting reflex happens very quickly, a distance of at least 10 feet is needed to allow the cat to completely right itself (Bradshaw, 2013). # References Bacon, B.A., Lepore F. and Guillemot, J-P. (1999) Binocular interactions and spatial disparity sensitivity in the superior colliculus of the Siamese cat. Experimental Brain Research 124, 181192. Bradshaw, J.W.S. (2013) Cat Sense : The Feline Enigma Revealed . Allen Lane, Penguin Books, London. Bradshaw, J.W.S., Casey, R.A. and Brown, S.L. (2012) The Behaviour of the Domestic Cat ,2nd edn. CAB International, Wallingford, UK. DeAngelis, G.C. (2000) Seeing in three dimensions: the neurophysiology of stereopsis. Trends in Cognitive Science 4, 8090. Heffner, S. and Heffner, H.E. (1985) Hearing range of the domestic cat. Hearing Research 19, 8588. Ley, J. (2016) Feline communication. In: Rodan, I. and Heath, S. (eds) Feline Behavioral Health and Welfare . Elsevier, St Louis, Missouri, USA. Loop, M.S., Millican, C.L. and Thomas, S.R. (1987) Photopic spectral sensitivity of the cat. Journal of Physiology 382, 537553. Miller, P.E. (2001) Vision in animals what do dogs and cats see? Waltham/OSU Symposium. Small Animal Opthalmology . Ohio State University, Waltham, Ohio, USA. Mills, D., Dube, M.B. and Zulch, H. (2013) Stress and Pheromonatherapy in Small Animal Clinical Behaviour . John Wiley & Sons, Ltd, Oxford, UK. Fig. 2.3. The righting reflex. As soon as the cat starts to fall the movement is detected by the vestibular system and within one tenth of a second the body starts to twist to allow the cat to land on its feet. Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions The Senses 21 Pasternak, T. and Merigan, W.H. (1980) Movement detection by cats: invariance with direc-tion and target configuration. Journal of Comparative and Physiological Psychology 94, 943952. Steinberg, R.H., Reid, M. and Lacy, P.L. (1973) The distribution of rods and cones in the retina of the cat ( Felis domesticus ). Journal of Comparative Neurology 148, 229248. Verrillo, R.T. (1966) Vibrotactile sensitivity and the frequency response of the Pancinian corpuscle. Psychonomic Science 4, 135136. Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions

Title:

URL Source: blob://pdf/b5229e63-188f-4b5f-a8c4-e4a8c6a21b7a

Markdown Content:
> 14  T. Atkinson, 2018. Practical Feline Behaviour (T. Atkinson)

# 2 The Senses

Because pet cats share our lives and our homes it can be easy to assume that their experience and perception of surrounding stimuli is the same as ours. But their sen-sory abilities, which have not changed from their wild ancestry, enable them to see, hear and smell things of which our senses leave us completely unaware. In a few respects, however, our senses are slightly better or at least just dissimilar but the over-all effect is that the cats view of the world is quite different to our own.

# Sight Night vision

There are a number of ways in which a domestic cats vision differs from human eyesight. The most well-known of these is the cats ability to see in the dark. In truth cats cannot see any better than we can in complete darkness but in low light conditions specific struc-tures of the feline eye allow them to utilize any available light far better than we can.

The retina of mammalian eyes contains two types of photoreceptors: rods and cones. Cones function best in bright light and are responsible for colour vision. Rods are more light sensitive and function better in reduced light to allow vision in low-light conditions. A cats retina contains far more rods than cones, with the total number of rods being around three times greater than is found in the human eye (Steinberg et al ., 1973).

The rod photoreceptor cells are not connected to fibres in the optic nerve individ-ually but are joined together in bundles, so that more visual receptors are con-nected to each nerve cell, resulting in even greater light detection. The disadvantage of this, however, is that it also reduces the clarity of the image (Miller, 2001).

Cats have very large eyes in relation to body size. At 22 mm in diameter, they are only slightly smaller than human eyes, which are 25 mm. The large size of the eyes along with elliptical pupils allow for pupil dilation that is at least three times greater than our own, enabling a large amount of light to enter the eyes when required. In bright light the elliptical pupil can be reduced by constriction of the iris to a very small vertical slit only 1 mm wide to protect the retina from damage. (Fig. 2.1).

A layer of reflective cells behind the retina called the tapetum lucidum  more specifically the tapetum cellulosum in cats and some other carnivores  reflects light that has not yet been absorbed by the photoreceptor cells back into the eye to allow another chance for absorption. This increases the efficiency of the eye in low light conditions by up to 40% (Bradshaw et al ., 2012). The tapetum is responsible for the characteristic reflective shine whenever a light is shone into a cats eyes. Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions The Senses  15

Movement detection

Rapid eye movements known as saccades prevent moving images from blurring and enable cats to detect and accurately track fast movements, even if the movement is slight or to the side of the cats direct line of vision. Sensory information regarding the distance and angle of the object is sent to the muscles surrounding the lens (the ciliary muscles) but, if this calculation is incorrect or if the object moves in an unex-pected way, a second corrective saccade follows the first to get the line of vision back on target. This corrective imaging can occur around 60 times per second, at least twice as fast as we are capable of (Bradshaw et al ., 2012). Slow movements, however, are not so well detected. Humans can detect move-ments that are ten times slower than those that can be seen by cats (Pasternak and Merigan, 1980).

Visual focusing

Visual focusing is one way in which our eyes perform much better than those of cats. In human eyes, the lens is flexible and, depending on the overall health of the eye, is able to focus fairly accurately by distortion of the lens. But the lens within a cats eye is inflexible and focuses by moving backward and forward rather than distorting. The result is that cats are a little slower at transferring their visual focus from near to distance and vice versa and are unable to focus clearly on anything that is less than 25 cm away from their face.

Colour vision

Perception of colour is another way that human vision is superior. Humans have three types of colour sensitive cone photoreceptors (red, blue and yellow) and 16 times more colour-comparing nerves than cats, which allow us to see a far wider range of different colours. Rod photoreceptors only allow for monochromatic vision and it was once thought that cats can only see in black and white. But neurophysiological evidence

> Fig. 2.1. Elliptical pupils can dilate more than round pupils, allowing more light to enter the eye. They can also constrict to very narrow slits to avoid damage to the retina from bright light. Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions 16 Chapter 2

shows that they possess two types of colour-sensitive cones that respond to light within the blue and green light spectrum, which means that they are likely to see yellow and blue as primary colours and their combination colours (Loop et al ., 1987). Behavioural research indicates, however, that cats colour perception may be muted or that they are behaviourally colour blind because they seem much more able to distinguish between differences in shape, pattern and brightness than between colours (Bradshaw et al ., 2012).

Binocular vision

Like us, cats have forward facing eyes that work together giving them stereoscopic or 3D vision (DeAngelis, 2000). This is achieved by each eye focusing on the same visual target and producing its own 2D image. These images overlap with each other result-ing in 3D vision. Stereoscopic vision is a great advantage for a predator because it allows for accurate judgment of depth and distance. Some Siamese cats have a genetic misrouting of retinal ganglion cells resulting in an inability to develop full stereoscopic vision (Bacon et al ., 1999). However, other than the development of an adaptational squint or cross-eyes, these cats appear otherwise unaffected and many are perfectly able to hunt successfully. Cross-eyed Siamese were quite common at one time, but are not seen so often now as more breeders have become aware of the genetic influence and choose not to breed from affected cats.

Field of vision

The field of vison is the area that can be seen when the eyes are fixed in one position. It is made up of the binocular visual field, where the two eyes work together to pro-vide a stereoscopic image, and the peripheral field which is outside of the central gaze and is non-binocular. Cats have about the same binocular field of vision as humans, about 90100. But their lateral peripheral visual field is wider, giving them a total of around 200 compared to around 180 in humans.

# Hearing

Cats have one of the widest ranges of hearing among mammals, extending from 48 Hz to 85 kHz (Heffner and Heffner, 1985), although it is generally accepted that the useful upper limit is more likely to be around 60 kHz because sounds above this frequency would have to be fairly loud for a cat to be able to hear them (Bradshaw

et al ., 2012). Even so, it is still quite exceptional when you consider that the average human hearing range is approximately 20 Hz to 20 kHz. The hearing range of most mammals encompasses that necessary to hear species-specific auditory communications plus, if a predatory species, the sounds made by prey. Hearing is one of the cats main methods of prey detection; it is therefore not surprising that their hearing range enables them to hear the very high-pitched ultra-sound signalling made by small rodents and other small prey species. But their hearing Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions The Senses  17

range also encompasses much lower frequency sounds than would be expected. This can be a particular advantage for pet cats because it allows them to hear the full range of human speech, even the low-pitched human male voice. Cats also have very sensi-tive hearing, allowing them to hear not just the vocalizations but also the movements of small animals and insects. Their ability to detect minor differences in pitch and intensity between sounds is, however, inferior to our own and they are less able to detect sounds of very short duration. Our increased ability in this respect might be due to our need to detect such small changes in sound that occur in human language (Bradshaw, 2013). The pinna (the external part of the ear) plays a very important role in both the location of sounds and as a directional amplifier. Individual muscles allow each pinna to be moved independently and these movements can be both rapid and precise ena-bling the cat to accurately pinpoint the source of a sound.

# Olfaction (Sense of Smell)

Olfaction is an extremely important sense for cats because it is used in communica-tion, reproduction, feeding and hunting. It is therefore not surprising that cats have a highly sensitive and discriminative sense of smell. Olfactory receptor cells, which have a direct neural connection to the olfactory bulb in the brain, are found in the olfactory epithelium  the lining of the nasal cav-ities. In humans this covers an area of around 25 cm 2 and contains around 5 million receptors. In cats the olfactory epithelium is supported by the scroll-like nasal turbinate bones, the ethmoturbinals, and covers a total surface area of approxi-mately 2040 cm 2 , containing around 200 million receptors (Ley, 2016). These are receptors of not just one type, but several hundred different types, enabling the cat to distinguish between an incredibly enormous number of different odours (Bradshaw

et al ., 2012).

The vomeronasal organ

The vomeronasal organ, also known as the Jacobsons organ, is an additional olfac-tory organ found in many mammals but not in humans or other higher primates. It provides the animal with a sense that is probably something between taste and smell and appears to be used primarily to detect and identify pheromones used in intra-species communication (see Chapter 3). It consists of two blind-ended fluid-filled sacs, situated within the hard palate, that contain around 30 different types of chemical receptors. Scent is actively taken in through the mouth and towards the vomeronasal organ via two small slits, known as the nasopalatine ducts, positioned just behind the upper incisors. When utilizing the vomeronasal organ, a cat will exhibit a slightly odd facial expression or grimace whereby the mouth is held slightly open with the upper lip raised (Fig. 2.2). This is also known as the flehmen response, from the German verb meaning to bare the upper teeth. Flehmen is a voluntary behaviour and it is possible that the presence of other visual or olfactory signals, such as the scent of urine, might trigger this reaction (Mills et al ., 2013). Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions 18  Chapter 2

# Touch The vibrissae (whiskers)

These are:

The mystacials: the large whiskers on either side of the nose.

The supercilliary: situated just above the eyes

The genals: smaller hairs situated on the side of the face.

Carpel hairs: found on the back of the forelegs. The whiskers, scientifically known as the vibrissae, are thickened hairs embedded deeply within the skin, around three times deeper than regular guard hairs. Large num-bers of mechanoreceptors, sensory neurons responsive to pressure or distortion, are found at the base of the vibrissae, making them sensitive enough to detect air currents. When the cat is hunting, the large facial whiskers (the mystacials) take over from the eyes to compensate for the cats poor close visual focusing. This is achieved by the whiskers being pushed forward to envelope the prey when it is close to the face enabling the cat to accurately detect and manipulate it. Cats are also able to get the best overall picture of their close surroundings and position in relation to nearby obstacles by com-bining visual input with sensory information from the whiskers (Bradshaw et al ., 2012).

The feet

A cats feet play an important role in hunting and defence, and are used to investigate and explore novel objects by touch. They are highly sensitive, containing a very high

Fig. 2.2.  The flehmen response, activating the vomeronasal organ.  Lucy Hoile. Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions The Senses  19

density of mechanoreceptors both in and between the pads and in the soft tissue at the base of the claws. Specialist mechanoreceptors known as Pacinian or Lamellar corpuscles in the deeper skin layers also allow cats to detect vibrations through the pads of the feet (Verrillo, 1966).

# Balance The vestibular system

The vestibular system is the part of the inner ear responsible for the sense of balance in mammals. It is made up of the semicircular canals, and the saccular and utricular otolith organs. The semicircular canals are three fluid-filled tubes that also contain motion-

sensitive hairs (cilia). They are:

The Horizontal : which detects turns to the left or right.

The Anterior and Posterior : which detect up and down movement and move-ments such as putting the head to one side. As the animal moves its head the vestibular system moves along with it but the fluid within the semicircular canals stays in place, thereby moving the hairs within the canals. The information about the movement is then relayed to the brain. The saccular and utricular otolith organs also have cilia covering their internal surface, but rather than fluid these organs have tiny calcite crystals covering the sen-sory surface that brush against the hairs as the animal moves its head. The otolith organs detect acceleration, deceleration and gravity, allowing the animal to know when and how fast it is moving, and when it is the right way up. Although this is the same system as in other mammals, including humans, the cats semicircular canals are much nearer to being at right angles to each other than in many other mammals and the horizontal canal is more parallel to the normal head position. This allows the information detected by the cilia within the canals and relayed to the brain to be particularly clear and precise. Plus, the utricular otoliths, and possibly the saccular, are much better attuned to measure gravitational deviations (Bradshaw et al ., 2012).

The Righting reflex

The righting reflex, sometimes called the air-righting reflex is the cats ability to land on its feet from a fall. When a cat starts to fall the movement is instantly detected by the vestibular system and within one tenth of a second the head starts to turn towards the ground, allowing the cat to see where it will land. The highly flexible spine allows the body to then twist, front end first and then the back end so that the cat is facing the ground. Lastly, as the cat is about the land, the back arches and the legs extend ready to act as shock absorbers (Fig. 2.3). If the fall is from a considerable height the legs are initially pushed out sideways and only extended downwards as the cat is just about to land. This has the effect of reducing the falling speed and probably accounts for reports of cats surviving falls Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions 20  Chapter 2

from tall buildings with only minor injuries. But this does not always prevent cats from sustaining serious injury as it can also depend on the nature of the surface on which the cat lands. Injuries can also occur if the distance that the cat falls is too short. Although the righting reflex happens very quickly, a distance of at least 10 feet is needed to allow the cat to completely right itself (Bradshaw, 2013).

# References

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Fig. 2.3.  The righting reflex. As soon as the cat starts to fall the movement is detected by the vestibular system and within one tenth of a second the body starts to twist to allow the cat to land on its feet. Downloaded from https://cabidigitallibrary.org by 128.120.235.240, on 02/11/23. Subject to the CABI Digital Library Terms & Conditions, available at https://cabidigitallibrary.org/terms-and-conditions The Senses  21

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Transcript for:Understanding Cat Sensory Abilities

Transcript for:
Understanding Cat Sensory Abilities