Scientists Peek Inside Snake's Fake Spider Tail

A snake in Iran has evolved one of nature's wildest tricks: a tail that looks so much like a spider that hungry birds can't resist attacking it.

The spider-tailed horned viper waves its unusual tail like bait, complete with what looks like a bulbous spider body and eight dangling legs. When a bird swoops down for an easy meal, the snake strikes and turns the tables.

Scientists first discovered a specimen of this snake in 1968, but researchers at the Field Museum thought the weird tail was just a tumor or deformity. The snake sat on a shelf for 35 years until another specimen with the same bizarre feature turned up in 2003.

By 2006, researchers realized they had a whole new species on their hands. A few years later, video footage captured the snake's hunting strategy in action, leaving scientists amazed.

"The appendage at the end of its tail is so outrageous," says Sara Ruane, Associate Curator of Herpetology at the Field Museum. "It's truly unique among snakes."

But until now, nobody knew what was happening inside that fake spider. Ruane teamed up with paleontologist Georgios Georgalis to scan the specimen using the Field Museum's new X-ray computed tomography lab, which can create 3D images of objects from thousands of X-ray photos.

The results surprised them. Despite the tail's wild appearance on the outside, the bones inside look completely normal for a viper. The snake achieved this incredible mimicry without drastically changing its skeleton, just the soft tissue and scales surrounding it.

The Ripple Effect

This discovery helps scientists better understand how animals evolve remarkable features without major structural changes. The finding also helps paleontologists identify fossil snake bones, since even unusual species can have typical skeletons.

The research shows that nature's most impressive adaptations sometimes come from small tweaks rather than complete transformations. Evolution found a way to create a perfect spider mimic using just modified scales and skin.

Scientists continue studying the specimen to understand exactly how the tail's spider illusion works so well. The snake remains one of the most fascinating examples of animal mimicry ever discovered.