Cat righting reflex
Encyclopedia
The cat righting reflex is a cat
's innate ability to orient itself as it falls in order to land on its feet. The righting reflex begins to appear at 3-4 weeks of age, and is perfected at 7 weeks. They are able to do this as they have an unusually flexible backbone
and no functional clavicle (collarbone). The minimum height required for this to occur in most cats (safely) would be around 1 m (3.3 ft). Cats without a tail also have this ability, since a cat mostly moves its hind legs and relies on conservation of angular momentum
to set up for landing, and the tail is in fact little used for this feat.
. They are able to accomplish this with these key steps:
Depending on the cat's flexibility and initial angular momentum, if any, the cat may need to repeat steps two and three one or more times in order to complete a full 180° rotation.
. Furthermore, once righted they may also spread out their body to increase drag and slow the fall to some extent.
A falling cat's terminal velocity is 100 km/h (60mph) whereas that of a falling man
in a "free fall position" is 210 km/h (130mph). At terminal velocity they also relax as they fall which protects them to some extent on impact. However, it has been argued that, after having reached terminal velocity, cats would orient their limbs horizontally such that their body hits the ground first.
, of 132 cats that were brought into the New York Animal Medical Center after having fallen from buildings, it was found that the injuries per cat increased depending on the height fallen up to seven stories but decreased above seven stories. The study authors speculated that after falling five stories the cats reached terminal velocity and thereafter relaxed and spread their bodies to increase drag
. However, an alternative interpretation which came out of internet chat of the study would be that upon an excess of seven stories the cats experience a higher fatality rate which precludes the owner from bringing them in for medical attention.
Although scientists in Massachusetts have recently discovered that the cat's ability to spread its legs out to decrease drag when reaching terminal velocity would explain the decreased injuries sustained above seven stories because they wouldn't reach terminal velocity
before then. Professor David Stevenson said "we simulated the cat's weight and size and found the terminal velocity to be 60mph which would more than likely result in severe injury or death to the cat when falling from this speed, but once we took into account the cat's ability to right its self and spread its body out this reduced the terminal velocity to only 53mph. this 7mph difference is massive and would almost certainly ensure the cat's survival. There however is always the possibility that the cat may not manage to right itself so this is far from a conclusive experiment and we do not condone the throwing of cats from anything".
Cat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
's innate ability to orient itself as it falls in order to land on its feet. The righting reflex begins to appear at 3-4 weeks of age, and is perfected at 7 weeks. They are able to do this as they have an unusually flexible backbone
Vertebral column
In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...
and no functional clavicle (collarbone). The minimum height required for this to occur in most cats (safely) would be around 1 m (3.3 ft). Cats without a tail also have this ability, since a cat mostly moves its hind legs and relies on conservation of angular momentum
Angular momentum
In physics, angular momentum, moment of momentum, or rotational momentum is a conserved vector quantity that can be used to describe the overall state of a physical system...
to set up for landing, and the tail is in fact little used for this feat.
Technique
After determining up from down visually or with their vestibular apparatus (in the inner ear), cats manage to twist themselves to face downward without ever changing their net angular momentumAngular momentum
In physics, angular momentum, moment of momentum, or rotational momentum is a conserved vector quantity that can be used to describe the overall state of a physical system...
. They are able to accomplish this with these key steps:
- Bend in the middle so that the front half of their body rotates about a different axis than the rear half.
- Tuck their front legs in to reduce the moment of inertiaMoment of inertiaIn classical mechanics, moment of inertia, also called mass moment of inertia, rotational inertia, polar moment of inertia of mass, or the angular mass, is a measure of an object's resistance to changes to its rotation. It is the inertia of a rotating body with respect to its rotation...
of the front half of their body and extend their rear legs to increase the moment of inertia of the rear half of their body so that they can rotate their front half quite far (as much as 90°) while the rear half rotates in the opposite direction quite a bit less (as little as 10°). - Extend their front legs and tuck their rear legs so that they can rotate their rear half quite far while their front half rotates in the opposite direction quite a bit less.
Depending on the cat's flexibility and initial angular momentum, if any, the cat may need to repeat steps two and three one or more times in order to complete a full 180° rotation.
Terminal velocity
In addition to the righting reflex cats have a number of other features that will reduce damage from a fall. Their small size, light bone structure, and thick fur decrease their terminal velocityTerminal velocity
In fluid dynamics an object is moving at its terminal velocity if its speed is constant due to the restraining force exerted by the fluid through which it is moving....
. Furthermore, once righted they may also spread out their body to increase drag and slow the fall to some extent.
A falling cat's terminal velocity is 100 km/h (60mph) whereas that of a falling man
Man
The term man is used for an adult human male . However, man is sometimes used to refer to humanity as a whole...
in a "free fall position" is 210 km/h (130mph). At terminal velocity they also relax as they fall which protects them to some extent on impact. However, it has been argued that, after having reached terminal velocity, cats would orient their limbs horizontally such that their body hits the ground first.
Injury
Using their righting reflex theory, cats can often land uninjured. This is, however, not always the case, and cats can still break bones or die from falls. In a 1987 study, published in the Journal of the American Veterinary Medical AssociationAmerican Veterinary Medical Association
The American Veterinary Medical Association , founded in 1863, is a not-for-profit association representing more than 81,500 U.S. veterinarians working in private and corporate practice, government, industry, academia, and uniformed services....
, of 132 cats that were brought into the New York Animal Medical Center after having fallen from buildings, it was found that the injuries per cat increased depending on the height fallen up to seven stories but decreased above seven stories. The study authors speculated that after falling five stories the cats reached terminal velocity and thereafter relaxed and spread their bodies to increase drag
Drag (physics)
In fluid dynamics, drag refers to forces which act on a solid object in the direction of the relative fluid flow velocity...
. However, an alternative interpretation which came out of internet chat of the study would be that upon an excess of seven stories the cats experience a higher fatality rate which precludes the owner from bringing them in for medical attention.
Although scientists in Massachusetts have recently discovered that the cat's ability to spread its legs out to decrease drag when reaching terminal velocity would explain the decreased injuries sustained above seven stories because they wouldn't reach terminal velocity
Terminal velocity
In fluid dynamics an object is moving at its terminal velocity if its speed is constant due to the restraining force exerted by the fluid through which it is moving....
before then. Professor David Stevenson said "we simulated the cat's weight and size and found the terminal velocity to be 60mph which would more than likely result in severe injury or death to the cat when falling from this speed, but once we took into account the cat's ability to right its self and spread its body out this reduced the terminal velocity to only 53mph. this 7mph difference is massive and would almost certainly ensure the cat's survival. There however is always the possibility that the cat may not manage to right itself so this is far from a conclusive experiment and we do not condone the throwing of cats from anything".
See also
- Falling cat problemFalling cat problemThe falling cat problem consists of explaining the underlying physics behind the common observation of the cat righting reflex: how a free-falling cat can turn itself right-side-up as it falls, no matter which way up it was initially, without violating the law of conservation of angular...
: the mathematical problem of explaining the physics of the cat righting reflex - Buttered cat paradoxButtered cat paradoxThe buttered cat paradox is a paradox based on the tongue-in-cheek combination of two adages:* Cats always land on their feet.* Buttered toast always lands buttered side down....
- High-rise syndrome