Owls Can Turn Their Heads All the Way Around

Owls have remarkable necks, but the rotation maxes out at roughly 270 degrees, three-quarters of a turn, not a full circle. That is still extraordinary and far beyond what a human neck can do, and owls need it because their eyes are fixed tubes locked in their sockets; they physically cannot swivel their eyeballs, so they move the whole head instead. To survive twisting their neck that far without cutting off blood to the brain, owls have special adaptations: extra neck vertebrae, and reservoirs and bypasses in their arteries that keep blood flowing even when vessels get pinched, which scientists at Johns Hopkins actually mapped. So the head turn is genuinely jaw-dropping engineering. It is just three-quarters, not the full Exorcist. Past about 270 degrees, the owl simply whips its head back the other way, fast enough that you might miss it.