To successfully catch prey and survive, predators in the animal world must adopt numerous diverse methods to secure a meal. From relying on cooperative pack hunting to raw power and rapid speed, predator’s techniques to snatch prey couldn’t be more different, especially for the Iranian spider-tailed viper.
Found across western Iran in the Zagros Mountains, the spider-tailed viper is endemic, therefore only living in that certain region. Throughout a prolonged period of time, the spider-tailed viper has adapted to attract prey in a notably unconventional, but genius fashion.
The viper’s tail has been crafted by evolution into a fleshy lure with elongated leg- like scales, closely resembling a spider. By utilising subtle tail movements, which is known as caudal mimicry, the snake can attract its favourite prey.
With the Ilam province of western Iran being a scorched arid climate, the appeal of food to some can be all too tempting. As migratory birds travel from Africa towards Europe and areas of Asia, some routinely stop within western Iran. By wiggling its tail, insectivorous birds are enticed by the fake spider. Once the birds have entered a close distance or even pecked the lure, the snake rapidly strikes. Through video studies, scientists have seen that the viper can strike in 0.2 seconds when grabbing birds straight out of the sky. Commonly, the snake has been found to primarily feed upon species of warbler and shrikes.
The great reed warbler, Acrocephalus arundinaceus, migrates from Sub-Saharan Africa to Eurasia in the spring, to breed. They commonly pass through the western region of Iran becoming prey for the Iranian spider-tailed viper.
PHOTOGRAPH BY Bildagentur Zoonar
Although extensive studies have not been carried out, small-scale ones have seen that birds permanently residing in western Iran, aren’t seemed to be preyed upon by the vipers. There’s a strong notion that resident birds have learned to identify the vipers, avoiding their lure, whilst the migratory birds from Africa have not.
Coupled with its rapid striking speed and ingeniously deceiving lure, the viper has another profound attribute contributing to its success. Its habitat is strewn with vast amounts of limestone and gypsum rock, which the snake has adapted to blend in with expertly camouflaging. As migratory birds come to eat the believed spider, they cannot see the snake's head perfectly placed right next to its own tail lure, ready to strike.
The spider-tailed viper is extremely camouflaged within its habitat, allowing it to go unseen as it traverses through the holes and tunnels to hiding spots, found within the limestone and gypsum rock formations.
PHOTOGRAPH BY Frank Deschandol
Due to a combination of difficulty spotting the camouflaged viper, their low population and small-scale searches, the snake was only officially named a species in 2006. Previously in 1968, an Iranian spider-tailed viper was studied, but the iconic lure was actually believed to be a birth defect, cancer or another spider like creature attached to its tail. Researchers didn’t understand its brilliance until more snakes were found with the same mysterious lure.
There have been very rare instances where the snake's lure has been pecked straight off by birds, revealing a clear vulnerability. How does it feed without this vital tool? Scientists are unsure about how much this snake depends on birds for its diet, with suggestions that it could feed on lizard species as well.
The spider-tailed viper, Pseudocerastes urarachnoides, is found in the Ilam province of western Iran.
PHOTOGRAPH BY Elena Odareeva
The physical anatomy of the spider-tailed viper is a fascinating example of how diverse and intricate evolution by natural selection can be. It’s not just this particular snake that utilises caudal mimicry, many other species of viper and pythons use it to trick prey.
The evolution of luring isn’t as simple as small tail wiggles and varying colours – it requires tail movement to be specific in imitating prey's movements in terms of directions and frequencies. How did something as complex as caudal mimicry evolve?
The Iranian spider-tailed viper’s lure is created as a result of elongated scales intended to look like a spider like creature to lure prey such as warblers.
PHOTOGRAPH BY Frank Deschandol
That question is still being heavily debated with ideas surrounding that it evolved from accidental tail movements. Once a stationary snake detects prey, it triggers excitation in the nervous system which ultimately is expressed as tail movements. Over time it’s believed this action favoured snake's survival and gradually developed into the viper's lure we see today.
Caudal luring however, isn’t just something that evolved in reptiles, we see it in other species such as fish. Evolution in the pelagic thresher shark has led to this creature developing an elongated whip shaped tail. As the shark circles certain fish, its tail attracts them, driving them into a compact mass before striking them with their thin tails to stun the prey and feed.
The pelagic thresher shark, Alopias pelagicus, utilises its massively long tail in order to attract prey before hitting the group of fish, leaving them stunned before the shark feeds.
PHOTOGRAPH BY Shane Gross
Back in the reptilian world, one certain snake, the puff adder, has been seen to not only utilise caudal mimicry with its tail but also use its tongue to lure prey, according to recent studies. By curling its tongue the snake aims to attract amphibians, but when using its tail lure, it aimed to attract mammals and birds in the area, from viewing extensive video evidence. This paints a picture that this certain snake has the ability to tell different species apart alluding to higher cognitive abilities than scientists first thought.
Alternatively, the spider-tailed viper in observation studies was seen to constantly wiggle its tail lure with or without the presence of birds. It is challenging to interpret if the snake doesn’t realise there is no prey or if the lure actually attracts more prey items other than birds such as amphibians or lizards. There just aren’t enough studies so far to be sure.
The puff adder, Bitis arietans, is found across Africa and is highly venomous being responsible for the most snakebite fatalities in Africa. It is believed that it uses its tail, and tongue, in order to attract different prey types.
PHOTOGRAPH BY Thorsten Spoerlein
The Iranian spider-tailed viper undeniably earns the right to owning the most astonishing, and to some horrifyingly, adapted lure in the reptilian kingdom. Without question, this species possesses one of the most memorable physical evolutions we have recently discovered, or have even ever seen.
Comments