A Shrewd Design

This X-ray image is of the hero shrew, a little-known mammal found in central East Africa. Turn-of-the-century explorers reported that the eight-inch-long shrew could support a full-grown man on its back. Dennis Cullinane, a graduate student in zoology at Cornell Veterinary College, came across these reports and decided to conduct a more rigorous study of the shrew. With the help of a local guide, Cullinane trapped one in Uganda, in a dense forest where the animal is fairly common, and took it to Cornell. The X-ray images he made show that the hero shrew has 11 vertebrae in its lower spine--most shrews have only 5 or 6--which makes it extremely limber. The vertebrae are three times wider than those of other shrews and also have interlocking, fingerlike projections that create sturdy links between neighboring vertebrae. That design may be the source of the shrew’s reputed strength. Since little is known of the shrew’s habits in the wild, no one knows why it might require unusual strength and flexibility. There’s nothing like it ever in the history of vertebrates, says Cullinane. Unfortunately, before he was able to test its strength, his specimen died. Cullinane plans to return to Uganda to find another shrew this year.