Heads will roll: Those elongated tubular eyeballs are very fetching (Wix)
It’s a well known fact that owls can turn their heads through 360 degrees. Except of course, they can’t.
An owl can actually, at most, only turn its head one way through roughly 135 degrees, giving it a total viewpoint of around 270 degrees—90 degrees short of a full circle. You can have that fact for free. Because what actually concerns us here is why owls have evolved to swivel their heads at all.
The answer to that? Well, owls have such extraordinarily mobile heads because their eyes, to put it bluntly, aren’t very mobile at all.
Us humans (I’m presuming you’re a human being reading this, of course) have eye balls: spheres that can roll in our eye sockets, giving us a wide, all-round field of vision—plus the ability to demonstrate just how totally done we are with everything.
Owls, however, don’t have eye balls but eye tubes: their eyes aren’t spheres, but vaguely elongated, slightly broad-based and misshapen cylinders that are locked in place in their head by tough bony plates called sclerotic rings. This bizarre set up gives the owl its unparalleled forward-facing, almost entirely binocular vision—but it also means that there’s no owl equivalent of a sarcastic eye roll. Alas.
So why do owls turn their heads? Yep, it’s because they are utterly unable to turn their eyes.