The Calabar burrowing python (Calabaria reinhardtii) is not nearly the biggest snake in the world, at only about a metre (three feet) long, and it's certainly not the most dangerous – it's non-venomous and preys on small animals – but a new study has found that its incredibly thick, armour-like skin makes it one of the toughest.

World's toughest snake? Meet the Calabar python (Calabaria reinhardtii). Image: Trisha Shears/Wikimedia Commons

These splotchy brown-and-yellow serpents – which, despite their common name, are actually boas and not pythons – spend much of their lives in the soil and leaf litter of Africa's warm forests. When predators come near, they show off their tails, which look – confusingly – very much like their heads. And when it's time for food, they dive into rodent burrows looking for their favourite meal: baby rodents.

But hunting babies comes with one major danger: the defensive parents of their chosen prey. During hunts, the snakes have been spotted suffering attacks from angry burrow guardians – and the bite of a rodent is no joke. The animals' big, sharp incisors can cause serious injury, and it's not unheard of for snakes to ultimately die as a result. But the Calabar species doesn't seem put off by the risk.

"[W]hen attacked or threatened, rather than fleeing, C. reinhardtii relies on passive-defensive behaviours, including coiling, hiding its head and elevating its tail (which is more brightly coloured than the rest of the body)," explains a group of Missouri-based researchers in a recently published study.

To find the secret of the snakes' resilience, the scientists scrutinised their skin. They measured its thickness, examined its microscopic structure and straight-up stabbed it with hypodermic needles (they did this with skin samples, not on living snakes!). They also performed similar tests on 13 other snake species from all around the world and with various lifestyles, including other boas, rattlesnakes, garter snakes and more.

The results? The skin of the Calabar python is like armour! Compared to other similarly sized snakes, the skin of this species is up to 15 times thicker, and its unique scale arrangement offers minimal weak points.

Their hides aren't totally puncture-proof, but it took way more force for those needles to punch through than for any other snake tested. And that means the teeth of angry mama rodents probably don't pose much of a problem.

How does the skin of the Calabar snakes achieve such durability while also being flexible? Part of that answer lies deep within their dermis, where bundles of collagen are arranged in highly organised criss-crossing layers. This is the same feature that makes rhino skin so tough. In fact, the researchers called the Calabar python "the rhinoceros among serpents".



Top header image: Screengrab (Science Magazine/YouTube)