Bill Stanley; Stanley et al. Biology Letters (2013)

ScienceShot: New Shrew Has Spine of Steel

It's the size of large rat, but it can reportedly withstand the weight of an adult man standing on its back. The Mangbetu people of the Democratic Republic of the Congo wore it as a talisman in battle, hoping for invincibility. Meet the hero shrew (Scutisorex somereni), a molelike creature that owes its near-mythological status to a remarkable spine, thickened by extensions of bone that interlock like fingers. The structure was thought to be unique among mammals—until now. An international team of researchers in the village of Baleko, in the Democratic Republic of the Congo, made a surprising find: a slightly different shrew with a similarly "heroic" backbone. Today in Biology Letters, they introduce Thor's hero shrew (S. thori), named for mammalogist Thorvald Holmes, but invoking the Norse god of strength. The new species (pictured) has a smaller and less bumpy skull; flatter ribs; and shorter, silkier fur than its sister species, the team reports, but genetic tests and x-rays reveal that it's undeniably Scutisorex (bottom spine, inset, as compared to S. somereni, middle, and a non-Scutisorex shrew, top). The researchers don't yet know how its strength compares to that of S. somereni. The team estimates that the two hero shrews diverged about 4 million years ago and think that the new species could be an intermediate step in the bizarre spinal evolution. After exploring the shrews' swampy palm forests habitat, the researchers also have a new guess about why the spine evolved: They suggest that the creatures might wedge themselves between the trunk of a palm tree and the base of its leaves, then use the strength and flexion of their muscular spine to force open this crevice, revealing insect larvae—a food source that other animals can't access. However, no hero shrew has yet been observed busting its back for a snack.

*Correction, 24 July, 12:30 p.m.: The article incorrectly stated that a shrew is a rodent. This has been fixed.