How do cats always land on their feet? Unlike toast, which really does land badly each and every time, cats hit the deck right side up. Far from being just an urban myth, the majority of felines dropped from a height manage to land on all fours; from your domestic moggy to the king of the beasts, feline agility is at work. While this isn’t a recent evolution, understanding feline physics could prove useful for modern scientists.
Does Feline Agility Defy Physics?
The falling cat question has been under scrutiny for a considerable number of years, puzzling many scientists. (There’s even a book about the phenomenon.) Back in 1894, Étienne-Jules Marey captured the arc of a cat falling on film, creating a slow-motion series of frames that showed what was happening. As Ars Technica describes, when it was first presented, Marey’s slo-mo cat fall led esteemed physicists to declare that cats were acting “against the known laws of physics.”
Regardless of feline agility defying physics, Marey’s film captured a cat showing the “bend and twist” necessary in mid-flight to bring its legs underneath its body for a safe landing. Each frame showed how the cat flexed its spine and rotated its legs to land “butter-side” up, so to speak.
How Do Cats Always Land on Their Feet?
Watching a caracal falling out of a tree also helps to further explain why feline agility is purr-fect for successful landings. In a BBC video, the wild cat, native to Africa, the Middle East, Central Asia, Pakistan and northwestern India, falls gracefully to the ground. Following the slow-motion frames, the narrator describes the sequence of events.
As the feline orientates itself in space to determine which way up it is facing, it starts a two-direction rotation. The forelimbs go clockwise while the rear spins counter to that. The cat holds its front legs close into its body similar to the way ice skaters do to increase speed of spin. This is key as it allows the animal to exert a force against the rest of its body, with the flexible spine allowing the rotations to continue. As the cat rights itself it brings all four feet underneath and arches its back to prepare to absorb the landing. Muscular and flexible limbs held perpendicular to the main body mass absorb the compression and impact forces for a successful landing.
The Benefits of Stomping the Landing
Landing correctly seems like a no-brainer, but not all animals manage this as effectively as the cat family. The reason for this, as a National Geographic video mentions, is that cats are tree dwellers, and all tree dwellers have an innate righting reflex.
As an evolutionary survival skill, it makes total sense that if you live above ground, being able to fall correctly is a bonus. Purina notes that this reflex develops from the age of three weeks in kittens and is complete at around seven weeks.
Cats have another advantage that makes them more likely to survive a fall: Their terminal velocity is low. Terminal velocity is the limiting uniform velocity attained by a falling body when the resistance of the air has become equal to the force of gravity. In other words, it’s the fastest speed a falling body gets to in free flight since resistance to the air limits the acceleration attained. Cats deploy a fluffy parachute by stretching themselves out, a little like a flying squirrel. This means that their terminal velocity is around 60 miles per hour (mph), whereas humans hit terminal velocity at 120 mph.
Science and the Falling Cat
Scientists have long been fascinated by falling cats, and veterinarians even more so by their survival rates. Although an earlier study seemed to suggest that falls from greater heights were more survivable, a 2003 paper in the Journal of Feline Medicine and Surgery pointed out that since owners rarely take deceased cats in for medical care, the study sample was skewed; falls from above seven stories often resulted in more severe injuries, although the survival rate was still remarkable compared with people falling the same distance.
Fascination for feline agility extends to robotics, where building machines that are capable of self-righting, landing correctly or surviving falls offers a lot more versatile. This curiosity also extends to space, where NASA studied how cats fell in order to coach their astronauts on how to move around in zero gravity.
One of the main problems encountered in falling is that there is often nothing to exert pressure against except your body itself. By studying how cats fall, NASA was able to break down the sequence of events into maneuvers that astronauts could use to re-orientate themselves in zero gravity. The scientists also discovered one amazing fact about feline agility: When falling, cats need gravity to orientate themselves for the bend and twist necessary to land successfully. In addition to using their eyes to check which way up they are falling, cats also need input from gravity. Gravity gives signals that alert the vestibular system in the inner ear and tell the cat which way it is pointing. As parabolic flight films show, cats lose their amazing righting reflex when dropped in zero gravity.
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