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This super 'hero' shrew has an unbreakable back

Hero shrews are small, ratlike mammals that are typically found in central Africa. These shrews have extraordinarily strong backbones.
Hero shrews are small, ratlike mammals that are typically found in central Africa. These shrews have extraordinarily strong backbones.William Stanley

A new species of hero shrew, recently found in Africa, is now known to be one of the strongest, sturdiest mammals in the animal kingdom.

The shrew, Scutisorex thori, measures less than a foot long and weighs only 1.7 ounces, and yet it can lift heavy logs. The appropriately named new "hero," found in the Democratic Republic of the Congo and described in the latest Royal Society Biology Letters, can also often survive attempted squishing.

Lead author William Stanley, of the Field Museum of Natural History, explained to Discovery News that locals used to demonstrate the sturdiness of these tiny mammals to scientists. When researchers first documented the genus back in the early 1900s, locals immediately recognized the furry shrew.

"'Oh, that’s the hero shrew,' they said," Stanley explained. “"We use it as a talisman. It renders us invincible to bullets and spears.'"

“At that point,” Stanley continued, “one of the men stood on the tiny mammal for 5 minutes. The shrew walked away unscathed.”

The new shrew, which sports thick, dark hair, appears to be just as strong.

Unique spine
Stanley and his team collected some of the mammals near the village of Baleko in the Congo. Detailed analysis of their body structure revealed that they are similar, yet distinctly different, from the other known hero shrew, Scutisorex somereni.

The most noteworthy feature that the shrews share in common is their unique spine.

“It’s massively reinforced, resulting in tremendous strength,” Stanley said.

An illustration of the hero shrew's skeleton.
An illustration of the hero shrew's skeleton. The ratlike animal has a bizarrely strong and oddly shaped backbone that has mystified scientists for more than 100 years.Velizar Simeonovski

He and his colleagues believe that the spine, along with associated muscles, allows the shrew “to leverage heavy objects, such as logs, enabling them to get to food that other animals cannot access.”

He shared that one of his colleagues, for example, lifted up material near palm trees and found “beetle grubs the size of sausages.” It’s likely that the hero shrew can position itself under a log or cracks underneath trees to hoist them upward, permitting consumption of the enormous grubs and other fare.

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At first it was thought that hero shrews somehow suddenly evolved their unusual spine, but the new species, which has a few less vertebrae than S. somereni, suggests that a gradual evolution took place.

The spine’s hefty bone-on-bone interlocking construction clearly serves the animals well. There are a few potential drawbacks, however. The shrews are a bit less flexible than other animals, such as other shrews and even humans, which have more typical spines.

That is a minor problem, though, given their ability to find worms, frogs and other prey attempting to hide at the base of trees and logs.

More to come
Kristofer Helgen, a research zoologist and curator-in-charge of the National Museum of Natural History’s Division of Mammals, told Discovery News, “I certainly agree with the paper's conclusions.”

“The discovery of another species of hero shrew is an outstanding find, and shows us how much of life on our planet, even among mammals, remains to be documented by scientists,” he continued. “The anatomy of this new species gives important clues about the evolution of the unusually strong spine in this group of shrews, and the authors of the paper provide the first compelling explanation for the adaptive significance of the unusual spine.”

Stanley, who just returned this week from another Congo trip, predicts that more new animal species will soon be found: “The age of discovery is not over.”