Why can cats fit into even the tightest spaces?

It is said that where a cat's head fits through, its body does too. Assuming, of course, that it hasn't put on a few extra pounds due to excessive snacking. But is it really true? Does it really depend on that?

Let’s see how the anatomy of a cat allows it to squeeze into impossibly small spaces.

Are cats liquid?

Cats are so flexible and agile that a 2014 study half-jokingly examined whether our pets are in a liquid state. While the researchers demonstrated good humor, they did take the question seriously. However, according to the rules of fluid mechanics, it seemed that they couldn’t provide an explanation for this mysterious ability of cats. Such extreme behavior in the animal kingdom may only be observed in octopuses.

The study, credited to Marc-Antoine Fardin, a physicist at the University of Paris Diderot, received the Ig® Nobel Prize that year. (The Ig® Nobel Prize is considered the pinnacle of scientific discoveries, awarded to research that first makes people laugh and then makes them think deeply.) Fardin concluded that depending on the situation, cats can be both liquid and solid. Liquid is defined as a substance that adjusts its shape to its container. Given enough time, cats conform to this definition. Images available on the internet perfectly support this theory, as we can see cats fitting into bowls, vases, wine glasses, or even the smallest boxes. But how do they do it?

The anatomy of the cat is the key

Their ability lies in the suspension of their forelimbs, or their shoulder girdle. In the case of humans, the shoulder girdle comprises the scapulae and the clavicle; the scapulae and clavicles are connected, providing rigid support to the muscles of the arms. In contrast, the scapulae and clavicles of cats are only connected to the rest of the body by muscles, not bones. Furthermore, a cat’s clavicle is much smaller relative to the rest of its body than ours compared to the rest of our body. These anatomical features allow our pets to squeeze through tiny openings, which is a huge evolutionary advantage for them. It helps them when hunting and also provides a significant advantage in escaping from predators.

In executing acts that would put Harry Houdini to shame, their whiskers, or vibrissae, are also a great help. Interestingly, the vibrissae sit three times deeper in the skin than the average hairs of cats. This is part of the reason why these hairs are so sensitive; they connect to nerve endings in the skin. The hairs pick up external stimuli and transmit information to the brain through the nerve endings. With the help of their whiskers, they can assess small spaces and easily determine whether they can fit through them or not. This talent can be compromised if a cat becomes overweight. With the cool weather upon us, let’s be very careful not to overfeed our indoor pets!