Zoologger is our weekly column highlighting extraordinary animals – and occasionally other organisms – from around the world

Video: Spider-hunting spider

Tougher than the rest (Image: Stano Pekár)

Species: Palpimanus gibbulus

Habitat: Mediterranean countries, particularly Spain and Portugal, lurking under rocks and tiptoeing towards other spiders

If you, like Mark Zuckerberg, plan to kill something and eat it, pick something that’s either smaller than you or can’t fight back, or preferably both. Otherwise you might bite off more than you can chew.


Not every predator takes things that easy. The desert long-eared bat happily munches on deadly scorpions, and recent footage showed a ground beetle tackling a toad several times its size. That’s impressive, but toads are not exactly vicious predators.

To really display your ballsiness as a predator, you need to take on other predators – preferably ones that would eat you given half the chance. That’s exactly what the spider-eating spider Palpimanus gibbulus does. This arachnid thug muscles its way into other spiders’ homes and attacks them head-on.

On the hunt

If you have never seen a P. gibbulus in action, you’re not alone. They hunt at night and are extremely rare, so we know very little about how they behave.

Stano Pekár of Masaryk University in Brno, Czech Republic, and colleagues wanted to find out how the spiders hunted. But they proved so elusive that the team had to combine P. gibbulus data with observations of a related species, Palpimanus orientalis. Found in Israel, P. orientalis is very similar to P. gibbulus: they can be distinguished only by looking at their sex organs.

The team captured spiders in pitfall traps and by searching under stones, and kept some of them in their lab. To find out what they could hunt, they tested 92 P. gibbulus and 65 P. orientalis. In each trial they put a single spider in a Petri dish, along with a single prey spider, and observed whether the Palpimanus could catch it.

It turned out they could catch each of the 29 kinds of spider they were offered, and caught all but one species in more than half the trials. It didn’t matter which family the prey came from, nor what size they were: Palpimanus was equally happy catching spiders a third its size or twice its size.

In one series of experiments, they presented P. gibbulus with a jumping spider called Cyrba algerina, which also habitually eats other spiders. P. gibbulus caught it in 90 per cent of trials, although in the other 10 per cent it was itself captured.

Armoured spider

What’s their secret? According to Pekár, Palpimanus have a battery of adaptations that help them hunt other spiders.

The most obvious is their massive front legs, which they use to grab their prey. Like many hunting spiders, they have dense tufts of extremely sticky hair on the tips of their legs. When Pekár glued these hairs together, the spiders became much less successful at hunting.

Palpimanus isn’t fast but it’s stealthy, closing on its prey so carefully that the prey may not be able to detect any vibrations from its footfalls. That means it can get up close, at which point it lunges, grabs the prey with its forelegs and administers a venomous bite.

In many cases the prey spider bites right back, but this doesn’t do it much good. Palpimanus has a cuticle tens of micrometres thick, over twice as thick as any of its prey species and possibly the thickest for a spider of its size, so bites rarely do it any harm. Apart from the trials with Cyrba algerina, only 1 per cent of trials ended with the prey species killing Palpimanus.

Pekár thinks that Palpimanus hunts by entering other spiders’ webs and burrows – a related Ugandan species has been seen doing just that. Confident in its armour, Palpimanus could trap its prey in their homes and overwhelm them.

Its intricate offensive strategy puts Palpimanus on a par with the more famous spider-eating spiders Portia. Found in tropical forests, Portia wait for their prey to be distracted by food before attacking, and sometimes twang their prey’s web to mimic the impact of a twig, disguising their approach. They can even plan new strategies to handle unfamiliar prey.

Can Palpimanus also learn and plan? There is much less information than there is for Portia, says Pekár, so we can’t say for sure. But Palpimanus does use different strategies for prey in webs, in nooks and crannies, and in the open, so it is versatile. Pekár suspects it can learn from its experiences and change its strategies accordingly.

Journal reference: Naturwissenschaften, DOI: 10.1007/s00114-011-0804-1

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