The secret to how cats twist in the air to land on their feet

When falling cats turn the right way before they hit the ground, they have a secret trick: an area of ​​their spine that twists exceptionally.

“We compared the flexibility of the thoracic spine and the lumbar spine in cats and found that the thoracic spine is very flexible,” he says Yasuo Higurashi at Yamaguchi University in Japan.

Cats are known to always land on their feet. If you hold the cat upside down and drop it, the animal will quickly curl up in the air and confidently land on its feet.

How cats achieve this has challenged scientists for over 100 years. They have three main ideas.

One of them is the propeller tail: the cat wags its tail to one side, which causes its body to turn to the other side. “The tail seems to be the least important, because if it doesn’t have a tail, it can tip over,” he says Greg Gbur at the University of North Carolina at Charlotte, author Falling felines and basic physics.

Another idea, the bending and twisting model, suggests that the cat bends its body almost to a right angle, then turns the front half to one side and the back half to the other. This means that both the front and back legs get into the correct position at the same time.

Or the cat could turn first the front and then the back in a tuck and turn. To do this, it extended its hind legs while keeping its front legs curled up, twisting its front half. Then he would switch so the front legs were extended and the back legs retracted, twisting his back half. This would mean that one pair of legs is correctly oriented in front of the other.

To find out what cats actually do, Higurashi and his colleagues conducted two experiments. In the first, they examined the spines of five deceased cats and twisted them to see how much each area could rotate without breaking. They focused on the thoracic spine, from the middle of the back, and the lumbar spine, from the lower back. The thoracic spine has been shown to have three times the range of motion of the lumbar spine.

Second, the team took high-speed video of two adult cats that were dropped from a height of 1 meter. In both cases, the cats completed the rotation of their forelimbs tens of milliseconds before their hindlimbs.

“My general impression is that bending and twisting is the most important thing, but this paper actually makes me rethink that a little bit and give a little more credence to tucking and twisting,” says Gbur. The highly flexible thoracic spine suggests to him that the front part of the cat’s body could rotate more. Moreover, in live experiments, “it really looks like a top [front] the body part is first correctly oriented”.

Gbur emphasizes that the models are not mutually exclusive. “Physicists in particular like to look for simple models of how things work, whereas nature tends to look for the most efficient method, which may not be simple,” he says. “Cats are complicated creatures that make complex movements.”

The study also revealed a strange detail. Both live cats turned to the right when they fell: one did so every time, the other in six out of eight trials. Gbur says an audience member at one of his lectures noticed that the cats in his videos also seemed to turn to the right. “It seems that, anecdotally at least, cats seem to have a rough preference for which way they curl,” she says. It is not clear why; it may be that an asymmetry in the placement of a cat’s internal organs means that it is easier to turn one way than the other.

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