Which of the following animals can't move its eyes?
Considering the chameleon, giraffe, owl, and gecko, the answer is: owl.
The eyes of an owl don't move like those of a human. Instead, owls have to move their entire head or body in order to look around. Luckily they have 14 neck vertebrae – twice as many as humans – which allows them to move their heads around 270 degrees.
Unlike humans, owls are born with just one socket for rotation. As compared to humans' two, owls' single pivot socket and multiple vertebrae allow the predator birds to rotate any which way they please. However, even with the muscular evolutionary adaptation, scientists were wary of just how these birds could whip their heads around without any internal damages. A research team from John Hopkins University discovered that owls have backup arteries, which offer a fresh supply of nutrients when blood vessels get closed off by rapid turning. Their arteries also swell to collect any excess blood created in the process.
Owls are not alone in this remarkable ability. Other birds, such as red-tailed hawks, are almost as flexible as their nocturnal cousins. Being able to check for danger behind and on all sides of you is a distinct perspective advantage, one that predatory birds greatly benefit from.
Check out a video of an owl twisting its head around below.