It looks like a spider and moves like a spider, but this is no spider – it’s an evolutionary nightmare. Watch the deadly killer in action

In the mountains of Iran, a flycatcher scans the area for something to eat – and spots a spider in a crevice.

But unfortunately for the bird, it isn’t actually a spider: it’s something far more dangerous (and venomous).

This bizarre attack is actually an evolutionary adaptation of the spider-tailed horned viper (which we named one of the weirdest snakes in the world), which belongs to a genus of snakes commonly known as ‘false-horned vipers’.

The viper’s tail is bulb-like with drooping scales, giving it the appearance of a spider.

The spider-horned viper uses its tail to trick and lure in birds, then strikes with its venomous bite – with the rest of its body well-camouflaged against the rocks.

While the viper’s venom is highly-specialised for birds, its affect on humans isn’t currently known.

So we don’t suggest being the first to find out…

This article by Sophie Ellis was first published by Discover Wildlife on 18 October 2025. Lead Image: A spider-tailed horned viper. Credit: Getty.

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