I’ve previously written a post on the spider-tailed viper (Pseudocerastes urarachnoides), a wonderful snake that has a bizarre and deceptively spider-like appendage on its tail. It was discovered in 1968 in Iran, but described as a new species only in 2006, with the authors speculating that the appendage could be used to lure prey. Below is a picture of the snake’s “caudal appendage” taken from the well-named website Life is short, but snakes are long (LISBSAL), which also describes the developmental basis of this structure:
. . . the structure of the [appendage], which is formed of the last pair of subcaudal scales, much enlarged, and a single enlarged dorsal scale. The elongated components are modified lateral scales. X-rays taken by the team showed that the caudal vertebrae extend well into this structure and are not deformed or modified.
So what we have here, as we nearly always do with new structures in evolution, is simply the modification of an old structure in a novel way. One could imagine that mutations that affected the rear scales, making them bigger and more spidery-looking, could give a reproductive advantage (more food!) to the mutant snake. Further mutations would make the lure even more spider-like and more attractive to prey. And perhaps the tail-waving was already in place, though it was surely elaborated after this structure began to evolve.
As I noted in my earlier post, this appendage could function to scare off predators, but the way the snake waves the appendage suggests that it’s a deceptive lure to attract prey who thinks they’re going to eat a juicy spider. Here’s a video of lure-waving:
Further, the informative post on LISBAL on “Spider-tailed adders” gives other information suggesting that this is indeed an evolved trait helping the snake capture prey, particularly birds:
Behavioral observations made in 2008 of a live P. urarachnoides captured in western Iran and maintained in captivity confirm these ideas. Closed-circuit video was used to record behavior, and the results published in the Russian Journal of Herpetology by Behzad Fathinia of Razi University and his colleagues. They observed the snake, a juvenile male that regurgitated a Crested Lark, using its caudal lure to attract sparrows and baby chickens that they introduced into its enclosure. When the birds approached and pecked the tail, the snake struck and envenomated the birds, a process taking less than one half second. A bird was also found in the stomach of the paratype specimen, further evidence that this species might feed heavily on birds in the wild with the aid of its spectacular caudal lure. The tail of P. urarachnoides probably represents the most elaborate morphological caudal ornamentation known in any snake, with the possible exception of the sound-producing rattles of rattlesnakes.
And, indeed, the video below, which came out a year after my first post, shows how the spider “lure” can attract a bird, which is then killed. This video is a bit heavy on rhetoric and light on science, but it still shows the effectiveness of the deceptive tail.
h/t: Mathieu
Since I learned of this viper no WEIT, I have been waiting for something like this! Fantastic!
The commentary is hilarious though 🙂
ZeFrank could do better. Or who was that Honeybadger guy?
Seriously impressive luring and predation video.
I’ve never heard of this species before. Fantastic! To me the tail, however, resembles a large centipede rather than a spider.
Whoops! The *stills* resemble a centipede but in the video the movement is *all* spider.
Yes that’s the first thing I saw when I saw the stills. ‘Centipede’ – ugh!
I don’t mind spiders but I loathe centipedes.
.. first thing I _thought_.
Oh for an Edit function…
That is cool. And kind of creepy …
Very creepy.
I’m sure there are people out there that are just quaking at the thought of a spider-snake combo. It’s phobia-palooza.
Speaking of ‘most whatever’, scientists have discovered the new ‘most’ — the teeth of the lowly limpet, which is now being touted as the strongest biological material, stronger than the strongest spider’s silk.
http://www.washingtonpost.com/news/morning-mix/wp/2015/02/18/scientists-have-discovered-natures-newest-strongest-material-and-it-comes-from-a-sea-snail/
That’s so interesting.
I now insist that all of my planes, boats, F1 racers and dental fillings be made from limpet teeth inspired materials!
In all seriousness though, it ‘s a good object lesson on how much we still have to learn about the oceans and the wildlife living therein.
If we’re making discoveries like this about gatrpods that live in tidal areas, Can you imagine what is waiting to be discovered at the bottom of the challenger deep?
Mimicry! I’d give my eye teeth to have a tail like that.
If you’ve got teeth in your eyes to give, you’ve already got quite enough in the anatomical anomalies department. Leave some for others.
😎
seems like such a case of natural selection. What other reason would cause this in a snake? g*d decided this particular snake needed some additional help. He didn’t even like snakes.
Caudal tail luring has been documented in several snake species – mostly vipers, but also in other ambush hunters like green tree pythons – so it seems like this is just a refinement of a strategy already in place. Some of the other snakes that do this have brightly colored, contrasting tails and others just do the motion without any modification of their tail.
https://www.youtube.com/results?search_query=caudal+tail+luring
Fascinating, I’ve never heard of this snake. It sure looked like a spider in the video or some such arthropod.
And speaking of snake appendages,
is it scientifically proven that rattle snakes use their rattles for “saying” watch-out, or our their other found uses for their rattle?
The rattle developed to protect them from deer, bison and other ungulates. The SantaCatalina Island rattler evolved where there are no large ungulates and the rattles devolved.
Fascinating!
How ismit possible to have lived for decades and never have heard of this snake before?What other secrets have been hidden from us?
You have to see it to believe it! Amazing (truly) to watch. Must be a challenge to molt out of all those spiny scale extensions.