Safety systems ensure blood supply
The investigations revealed a clear difference to the neck anatomy of humans: The vertebral holes through which one of the carotid arteries from the body of the owl in the head, are significantly larger than the blood vessel itself. This leaves the vein space for movement, the researchers explain. In contrast, the human arteries fit snugly in the vertebral holes. In addition, owls still have special "safety arteries" in the neck, which allow emergency care, if it should actually pinch, the researchers report. In addition, Gailloud and his colleagues discovered bulges in blood vessels in the upper part of the neck, which presumably additionally serve as a blood reservoir in case of an extreme twisting of the head. "All of these protection systems are missing from humans, so extreme turns of the head, for example in accidents, are life-threatening for us, " says Gailloud.
The hypermobile neck has an important function for the owls in their way of life as Lauerjäger. In order not to scare prey animals such as mice, they must be quiet and unobtrusive, but still be able to monitor the largest possible area. Therefore, they sit motionless, only the head turns gently and silently. The rotation also compensates that the birds are unable to move their eyes independently of the head. At least as important, however, is the flexible alignment of the ear: In owls, the so-called veil - the ring-shaped feathers around the eyes - forms a kind of sound funnel that directs sound directly to the ear openings. By turning the head, owls can precisely align this sophisticated hearing system to noise sources. The combination of an extremely rotatable head with directional gaze and sensitive hearing allows owls to precisely locate both the finest twitching of a mouse's tail and the slightest rumbling on a crumb. displayPhilippe Gailloud (Johns Hopkins University School of Medicine) et al .: Science, Acknowledgment in Issue 1 FEBRUARY 2013 VOL 339 © wissenschaft.de - Martin Vieweg