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 6–9 weeks.[1] Cats are able to do this because they have an unusually flexible backbone and no functional clavicle (collarbone). The tail seems to help but cats without a tail also have this ability, since a cat mostly turns by moving its legs and twisting its spine in a certain sequence.[2]
While cats provide the most famous example of this reflex, they are not the only animal known to have a mid-air righting capability. Similar phenomenons have been observed in other small vertebrates such as rabbits,[3] rats,[4] lizards, and certain invertebrate tailed anthropods (e.g. stick insects).[5]
Technique
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After determining down from up visually or with their vestibular apparatus (in the inner ear), cats manage to twist themselves to face downward without changing their net angular momentum. 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 from the rear half.
- Tuck their front legs in to reduce the moment of inertia 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 by as much as 90° while the rear half rotates in the opposite direction as little as 10°.
- Extend their front legs and tuck their rear legs so that they can rotate their rear half further while their front half rotates in the opposite direction less.
Depending on the cat's flexibility and initial angular momentum, if any, the cat may need to perform steps two and three repeatedly to complete a full 180° rotation.[6][7][8]
Terminal velocity
editIn addition to the righting reflex, cats have other features that reduce damage from a fall. Their small size, light bone structure, and thick fur decrease their terminal velocity. While falling, a cat spreads out its body to increase drag.[9] An average-sized cat with its limbs extended achieves a terminal velocity of about 60 mph (97 km/h), around half that of an average-sized man, who reaches a terminal velocity of about 120 mph (190 km/h).[10] A 2003 study of feline high-rise syndrome found that cats "orient [their] limbs horizontally after achieving maximum velocity so that the impact is more evenly distributed throughout the body".[11]: 311
Injury
editWith their righting reflex, cats often land uninjured. However, this is not always the case, since cats can still break bones or die from extreme falls. In a 1987 study, published in the Journal of the American Veterinary Medical Association, of 132 cats that were brought into the New York Animal Medical Center after having fallen from buildings, it was found that injuries per cat increased positively with altitude until a height of seven stories, at which point injuries decreased. One cat fell 40 stories without injury, having apparently bounced off a canopy and into a planter.[12] The study's authors speculated that, after falling five storeys, the cats reached terminal velocity, at which point they relaxed and spread their bodies out to increase drag. However, critics of the study have questioned the conclusion that mortality rates decrease as height increases due to survivorship bias; falls that resulted in instant death were not included as a deceased cat would not be brought to a vet.[12] A 2003 study of 119 cats concluded that "Falls from the seventh or higher storeys, are associated with more severe injuries and with a higher incidence of thoracic trauma."[13]
See also
edit- Falling cat problem – the mathematical problem of explaining the physics of the cat righting reflex
- High-rise syndrome – veterinary terminology for injuries sustained by cats typically caused by falls from significant heights
- Buttered cat paradox – a humorous combination of two observations, the cat righting reflex and the buttered toast phenomenon
References
edit- ^ Sechzera, Jeri A.; Folsteina, Susan E.; Geigera, Eric H.; Mervisa, Ronald F.; Meehana, Suzanne M. (December 1984). "Development and maturation of postural reflexes in normal kittens". Experimental Neurology. 86 (3): 493–505. doi:10.1016/0014-4886(84)90084-0. PMID 6499990. S2CID 23606824.
- ^ Nguyen, Huy D. "How does a Cat always land on its feet?". Georgia Institute of Technology, School of Medical Engineering. Archived from the original on 2001-04-10. Retrieved 2007-05-15.
- ^ Schönfelder, J. (March 1984). "The development of air-righting reflex in postnatal growing rabbits". Behavioural Brain Research. 11 (3): 213–221. doi:10.1016/0166-4328(84)90213-4. ISSN 0166-4328. PMID 6721914 – via PubMed.
- ^ Yan, Xinping; Okito, Kazuyoshi; Yamaguchi, Takashi (March 2010). "Effects of superior colliculus ablation on the air-righting reflex in the rat". The Journal of Physiological Sciences. 60 (2): 129–136. doi:10.1007/s12576-009-0076-0. ISSN 1880-6562. PMC 10717533. PMID 20047100.
- ^ Jusufi, Ardian; Zeng, Yu; Full, Robert; Dudley, Robert (19 September 2011). "Aerial Righting Reflexes in Flightless Animals". Integrative and Comparative Biology. 51 (6): 937–943. doi:10.1093/icb/icr114. PMID 21930662 – via Oxford Academic.
- ^ Fink, Hardy (February 1997). "An insight into the Biomechanics of Twisting". Technique. 17 (2). USA Gymnastics. Archived from the original on 1998-05-28. Retrieved 2007-12-26.
- ^ Calle, Carlos I. (2001-10-10). Superstrings and Other Things: A Guide to Physics. CRC Press. pp. 106, 107. ISBN 9780750307079. Retrieved 2008-06-04.
- ^ Kane, Thomas; Scher, M. P. (1969). "A dynamical explanation of the falling cat phenomenon". International Journal of Solids and Structures. 5 (7): 663–670. doi:10.1016/0020-7683(69)90086-9.
- ^ Hutchinson, J.R. (11 January 1996). "Vertebrate Flight: Gliding and Parachuting". University of California Museum of Paleontology. Retrieved 22 December 2016.
- ^ Nasaw, D. (25 March 2012). "Who, What, Why: How do cats survive falls from great heights?". BBC News Online. Retrieved 22 December 2016.
- ^ Vnuk, D.; Pirkić, B.; et al. (18 June 2003). "Feline high-rise syndrome: 119 cases (1998–2001)". J Feline Med Surg. 6 (5): 305–12. doi:10.1016/j.jfms.2003.07.001. PMC 10822212. PMID 15363762. S2CID 40989939.
- ^ a b Adams, Cecil (1996-07-19). "The Straight Dope: Do cats always land unharmed on their feet, no matter how far they fall?". The Straight Dope. Archived from the original on 2000-08-15. Retrieved 2008-06-04.
- ^ Vnuk, D.; Pirkić, B.; Matičić, D.; Radišić, B.; Stejskal, M.; Babić, T.; Kreszinger, M.; Lemo, N. (1 October 2004). "Feline high-rise syndrome: 119 cases (1998–2001)". Journal of Feline Medicine and Surgery. 6 (5): 305–312. doi:10.1016/j.jfms.2003.07.001. PMC 10822212. PMID 15363762. S2CID 40989939.
Further reading
edit- Arabyan, A.; Tsai, D. (1998). "A distributed control model for the air-righting reflex of a cat". Biol. Cybern. 79 (5): 393–401. doi:10.1007/s004220050488. PMID 9851020. S2CID 6443644.
- Diamond, J. (1988). "Why cats have nine lives". Nature. 332 (6165): 586–587. Bibcode:1988Natur.332..586D. doi:10.1038/332586a0. PMID 3357516. S2CID 4241224.
- Gbur, Greg (2019). Falling Felines and Fundamental Physics. New Haven, CT. ISBN 978-0-300-24907-1. OCLC 1122457477.
{{cite book}}: CS1 maint: location missing publisher (link) - Laouris, Y.; Kalli-Laouri, J.; Schwartze, P. (1990). "The postnatal development of the air-righting reaction in albino rats. Quantitative analysis of normal development and the effect of preventing neck-torso and torso-pelvis rotations". Behavioural Brain Research. 37 (1): 37–44. doi:10.1016/0166-4328(90)90070-U. PMID 2310493. S2CID 10542756.
- Laouris, Y.; Kalli-Laouri, J.; Schwartze, P. (1990). "The influence of altered head, thorax and pelvis mass on the postnatal development of the air righting reaction in albino rats". Behav. Brain Res. 38 (2): 185–190. doi:10.1016/0166-4328(90)90016-8. PMID 2363837. S2CID 8325481.