Why can a kitten huddle in a box? This is because cats have an instinct to find enclosed spaces, as this makes them feel safe. In the wild, cats will look for small spaces to hide from predators or rest and preserve energy. This instinct still exists in domestic cats, which is why they often look for boxes or other enclosed spaces to curl up. In addition, the box provides cats with ownership and control over the environment, which is important for their health.

Kittens can shrink in the box because cats have many and small bones. They have 290 bones, 84 more than the human body. Moreover, these bones are smaller and their joints are softer, so they can "flow everywhere" freely like liquid.

The distance between the spines of cats is quite large, and thick, soft, elastic fiber cartilage is interspersed with. In addition, the cat's scapula is only connected to the muscles on the side, allowing its joints to move in all directions, while the cat's flowing clavicle allows the cat to make long-distance steps.