Mice have an amazing ability to fit in extremely small areas. But, contrary to what people may think, they do have bones.
Mice are incredibly flexible – to the point where this ability seems out of this world, making everyone wonder how these animals can get inside the house.
What is the smallest hole a mouse can get through?
Even if there is a small gap, these rodents will squeeze through as long as the hole is wide enough to fit their head. In fact, they even measure the possibility of traversing the opening by checking its size with their heads. The rest is easy for them.
Rodent specialists say that holes the size of a dime (10-cent coin in the US) are enough to accommodate a mouse. This means openings less than 18 mm (0.71 inches) in diameter are good to go for a mouse.
Here you can see an interesting experiment where the author tests the ability of this animal to squeeze through different holes drilled according to precise measurements:
What bones form the skeleton of a mouse?
Mice are vertebrates. Thus, they have a skeleton similar to that of other mammals. They have an elongated skull that protects the brain. Five cranial ridges unite different bones of the skull. The spinal column of mice is made up of 24-26 vertebrae, which allow the body to articulate and avoid injuries to the nervous system.
Twenty more vertebrae compose their tail. The little rodents have 13 flexible ribs, protecting organs such as the heart or lungs. Pelvis provides the mice with mechanical support and protects the pelvic organs. And, of course, mice have four limb bones which let them move fast. They do not have a collarbone like humans, which even further advances their ability to ‘collapse’ their skeleton.
In total, mice have more than 200 small bones.
What is the secret behind the extraordinary flexibility of mice?
But why are the mice so flexible?
These abilities are not magic – mice evolved to be able to squeeze into tight spaces. They have lots of flexibility between all the small vertebrae that make up their spine and ribs. Therefore, these bones can bend very easily and reduce the body dimensions to a minimum.
The narrow thorax also allows them to enter small spaces. When a mouse tries to pass through a narrow crack, it first checks if its head can fit using its sensory organs, whiskers, or limbs. And, if their head can go through, the rest of their body will be able to squeeze through too.
What about the flexibility of rats?
By the way, the flexibility of rats is basically on the same level, it’s just that rats a bigger. Average-size specimens weighing up to 200 grams can pass through holes the size of a nickel (5-cent coin in the US), or 21.21 mm (0.835 inches) in diameter.
Watch the following video where you can observe how a rat is able to get into a house through narrow maze-like toilet pipes. Even their abilities to navigate in confined spaces are amazingly good!
If you see a mouse in your house, don’t be surprised. It probably got in through some small crevice that you have never thought would be large enough to fit this rodent. In any case, it could be worth consulting pest control services if you wish to resolve this issue for good.