Mammals
Hero Shrew
Scutisorex somereni · also called armoured shrew, Ikakinene
From the neck up, the hero shrew is an ordinary large shrew snuffling through the leaf litter of the Congo rainforest. Its spine is not ordinary at all. It is built like a piece of engineering, and it can take the weight of a standing adult human.
Overview
Scutisorex somereni lives on the floor of the Congo Basin rainforest, hunting earthworms and insect larvae. Above the neck it looks like a normal grey-brown shrew, about 12 to 15 cm long.
The armoured spine
Its lower backbone has extra vertebrae, each covered in dense interlocking bony spines that mesh above, below, and on the sides, turning the spine into a rigid but flexible tube far stronger than any comparable mammal’s. The Mangbetu people of the Congo showed early explorers a man standing on the animal, which then walked away unhurt — the origin of its name.
What it is for
The purpose is still uncertain. The best idea is foraging leverage — bracing the whole body to pry apart logs and bark to reach hidden prey. A second species found in 2013, with a partly interlocked spine, shows the trait could have built up gradually.
Status
Least Concern — fairly widespread in central African forest and tolerant of some disturbance, though naturally uncommon and little studied.
Hero Shrew: common questions
Can a person really stand on a hero shrew?
According to the accounts that gave the animal its name, yes. When Western scientists first encountered the shrew in the early twentieth century, local Mangbetu people in the northeastern Congo described how an adult could place a foot on the animal, put their full weight on it, and step off, after which the shrew would shake itself and walk away apparently unharmed. This was demonstrated to researchers. It is not something anyone should try casually, and a modern welfare view would not repeat the stunt, but the shrew's spine genuinely can bear loads that would crush the backbone of any other mammal its size.
What is so special about its backbone?
An ordinary mammal has vertebrae that connect to their neighbours at a few small joints. In the hero shrew, the vertebrae of the lower back are more numerous than normal and each one is covered in a dense growth of tiny bony spines, or tubercles, that mesh with the spines of the vertebrae in front and behind, and also with those to the sides, so the whole lower spine locks together into a stiff, interlaced, load-spreading structure while still being able to bend. Nothing else among mammals, living or fossil, has anything close to it, which is why the anatomy has fascinated biologists for a century.
Why did it evolve such a strong spine?
This is still an open question, because nobody has watched a wild hero shrew closely enough over a long enough period to be sure. The leading hypothesis is foraging leverage, meaning the shrew may use its rigid, powerful body as a bracing tool to push apart the bases of palm fronds, lever up loose bark and logs, or force its way into packed leaf litter and rotting wood, reaching worms and insect larvae that are sealed away from other predators. The discovery of a second species with a partly interlocked spine supports the idea that the trait built up gradually because each small increase in stiffness was useful.
Is the hero shrew rare or endangered?
It is listed as Least Concern. It is spread across a fair area of the Congo Basin forests, occurs in several countries, and can persist in disturbed and secondary forest and old plantations, so it is not thought to be at risk as a species. That said, it is naturally thin on the ground, notoriously difficult to catch in standard small-mammal traps, and little studied, so its numbers and trends are genuinely not well known, and the ongoing clearance of central African forest is a concern for it as for most forest wildlife.