One study shows that woodpecker eyes are held tightly in place by bone and surrounding tissue, unlike human eyes, which have room to move around within the sockets.

• 一项研究表明,啄木鸟的眼睛被周围的骨骼和组织紧紧包围着,而这一点与人类眼睛的结构并不一样,人的眼珠可以在眼眶中转动。