A squirrel, like other rodents, has surprisingly strong teeth.
In the front part of the mouth, there are protruding chisel-shaped incisors that continue to grow throughout the animal's life, wearing down. With their help, as well as powerful muscles in the lower jaw, the creature can break and gnaw hard food. The molars are located at the back of the mouth.
It is interesting how a squirrel cracks a nut. It sinks both lower incisors into the spot where the nut is connected to the twig. The uniqueness lies in the fact that the lower jaw of squirrels consists of two halves connected by an elastic muscle. When the squirrel slightly compresses them, the incisors spread apart and, like a wedge driven into a crack, split the nut in half. This process is described by the famous Polish zoologist and popularizer Jan Żabiński in his book "From the Life of Animals."
Can such a simple and elegant way of cracking a nut be innate? It turns out, no.
The largest Dutch ethologist and Nobel Prize laureate Nikolaas Tinbergen, in his book "Animal Behavior," recounts an experiment conducted at the Max Planck Institute (Germany). Researcher Irenäus Eibl-Eibesfeldt raised squirrels in natural conditions but did not give them any nuts until they were fully grown. Here’s what he managed to find out.
An adult squirrel that had never seen a hazelnut was able to handle it only through great perseverance. As a result of its efforts, this squirrel was left with a mangled shell marked by numerous failed attempts.
The next attempts were more successful. The squirrel gnawed through several nuts and learned to focus its efforts on a specific area of the shell. It realized that the base of the nut was softer, made connecting grooves in it, and began to bite off the shell in pieces. However, the work still took the creature a lot of time.
Finally, all the meat was extracted at once. The squirrel, discovering a natural groove in the shell, deepened it with its teeth, like a chisel, and cracked the nut without much effort.
Thus, through practice, the optimal way of cracking the nut was found. By trial and error, the squirrel gained individual experience.
For more details, see: https://www.nkj.ru/archive/articles/713/ (Science and Life, HOW A SQUIRREL GNAWS NUTS)
