I had never really thought much about what makes owls turn their heads until I actually saw one do it in person, it was also at night and at the backyard so it was a bit scary for me. They are literally looking at you from right behind their own backs when they do that.
They have 14 neck vertebrae and human beings only have 7, which gives them a lot more range of motion when it comes to bending their necks without breaking something crucial.
https://youtube.com/shorts/aqhrkUZkK-c?si=eWnPvYjRajBtJOit
But the fact that they have more bones in this area than we do isn’t even the cool part, the vessels in their neck carry blood through huge holes in their vertebrae that are way bigger than the size of the vessels, so when they turn their heads and everything inside gets squeezed, the vessels are just moved around instead of tearing or getting crushed. Also owls have these little pools of blood at the back of their heads that give them backup blood flow to the brain while the primary blood vessels are being pinched shut.
All this is because owls cannot move their eyes at all, and because their eyes are shaped like tubes instead of round balls, their eyes are always looking directly at what is in front of them, so if an owl wants to see something to its left, it has to turn its whole head to do it.
Studying the biology of this animal, it seems like excessive engineering just so owls can look at something on their left side. But it is also necessary for survival. They must have an ability to see every single thing without making noise while they are moving every part of their bodies while hunting for mice in the middle of the night.
Even so, it is a strange thought to have about how much natural biological evolutionary engineering goes into just being able to look sideways like that. I may be scared of them but they make good pets.