Some animals are known to use parts of their bodies as luries to entice and capture prey. But this snake, the recently described and aptly named spider-tailed viper, has taken the trick to the next level.


This snake was only confirmed as a new species in 2006, but locals have known about it for years. Found in the deserts of western Iran, scientists thought that the object on the end of its tail was a tumor or growth. But after discovering other snakes with similar features, they realized that it was an actual part of the animal's physiology. And in fact, it both looks and moves like a spider — abdomen, legs, and all.


Credit: Omid Mozaffari.

Ed Yong describes the tail's possible function:

It’s probably a lure, like a fisherman’s fly. By resembling a tasty morsel, it draws potential prey into the snake’s striking range. [Behzad] Fathinia tested this idea by putting a chick into the same enclosure as his captive viper, which duly undulated its tail. “It was very attractive and looked exactly like a spider moving rapidly,” Fathinia wrote. “After approximately half an hour, the chick went toward the tail and pecked the knob-like structure. The viper pulled the tail structure toward itself, struck and bit the chick in less than 0.5 seconds. The chick died after 1 hour.” A sparrow met the same fate. Many snakes use similar “caudal lures” like this, including death adders (see video), some boas, and many vipers. But usually, these lures are nothing fancier than a thin tail tip that wriggles like a worm. If that’s good enough to attract a lizard or frog, why has the spider-tailed viper evolved a tail that’s so much more elaborate?

The function and the origin of the spider-tailed viper’s spider tail, says Yong, is still a mystery.

Read all of his account at his Not Exactly Rocket Science column over at National Geographic.