More astounding spiders

Here’s another unbelievable—in terms of both evolution and videography—segment from Attenborough’s BBC Earth. Jumping spiders in the genus Portia are said by Wikipedia to be “remarkable for their intelligent hunting behaviour”, and you won’t deny that after watching this 4-minute video. According to Attenborough, this beast has “three superpowers”. Her speed and intelligence are remarkable!

Here’s what Wikipedia says about their smarts and hunting behavior:

Brains:

Portia often hunt in ways that seem intelligent. All members of Portia have instinctive hunting tactics for their most common prey, but can improvise by trial and error against unfamiliar prey or in unfamiliar situations, and then remember the new approach.

They are capable of trying out a behavior to obtain feedback regarding success or failure, and they can plan ahead (as it seems from their detouring behavior).

Portia species can make detours to find the best attack angle against dangerous prey, even when the best detour takes a Portia out of visual contact with the prey, and sometimes the planned route leads to abseiling down a silk thread and biting the prey from behind. Such detours may take up to an hour, and a Portia usually picks the best route even if it needs to walk past an incorrect route.  If a Portia makes a mistake while hunting another spider, it may itself be killed.

Portia uses trial-and-error to successfully solve a confinement problem (i.e. how to escape from an island surrounded by water) both when correct choices are rewarded and when incorrect choices are punished.

Nonetheless, they seem to be relatively slow “thinkers”, as is to be expected since they solve tactical problems by using brains vastly smaller than those of mammalian predators. Portia has a brain significantly smaller than the size of the head of a pin, and it has only about 600,000 neurons, hundreds of thousands of times fewer than the human brain.

Hunting:

Their favorite prey appears to be web-building spiders between 10% and 200% of their own size. Portia look like leaf detritus caught in a web, and this is often enough to fool web-building spiders, which have poor eyesight.

When stalking web-building spiders, Portia try to make different patterns of vibrations in the web that aggressively mimic the struggle of a trapped insect or the courtship signals of a male spider, repeating any pattern that induces the intended prey to move towards the PortiaPortia fimbriata has been observed to perform vibratory behavior for three days until the victim decided to investigate.  They time invasions of webs to coincide with light breezes that blur the vibrations that their approach causes in the target’s web; and they back off if the intended victim responds belligerently. Other jumping spiders take detours, but Portia is unusual in its readiness to use long detours that break visual contact.

Laboratory studies show that Portia learns very quickly how to overcome web-building spiders that neither it nor its ancestors would have met in the wild. Portia‘s accurate visual recognition of potential prey is an important part of its hunting tactics. For example, in one part of the Philippines, local Portia spiders attack from the rear against the very dangerous spitting spiders, which themselves hunt jumping spiders. This appears to be an instinctive behavior, as laboratory-reared Portia of this species do this the first time they encounter a spitting spider. On the other hand, they will use a head-on approach against spitting spiders that are carrying eggs. However, experiments that pitted Portia against “convincing” artificial spiders with arbitrary but consistent behavior patterns showed that Portia‘s instinctive tactics are only starting points for a trial-and-error approach from which these spiders learn very quickly.

Against other jumping spiders, which also have excellent vision, Portia may mimic fragments of leaf litter detritus. When close to biting range, Portia use different combat tactics against different prey spiders. On the other hand, when attacking unarmed prey, such as flies, they simply stalk and rush, and they also capture prey by means of sticky webs.

I had no idea what spitting spiders were, so I went to the link, and learned that they’re a group that spits a mixture of sticky silk and venom at their prey, entangling it in a mesh that also paralyzes it. It’s remarkable, and here’s a video from National Geographic:

And the battle of the titans: a jumping spider battles a spitting spider. Guess who wins?

14 Comments

  1. BJ
    Posted July 4, 2017 at 1:08 pm | Permalink

    Damn you, Jerry! Where’s my trigger warning?!?

    Why do the have so many eyes if not for figuring better strategies to attack me and eat my face? I don’t trust them.

  2. Posted July 4, 2017 at 1:38 pm | Permalink

    Very good, especially the one on Portia.
    I have not seen a spitting spider, though they occur here in the U.S. I always have fun watching the many species of jumping spiders. They are by far the most charismatic of spiders.

  3. Jenny Haniver
    Posted July 4, 2017 at 1:42 pm | Permalink

    Wowie!

  4. Tom
    Posted July 4, 2017 at 2:59 pm | Permalink

    Here in the South Midlands UK I usually have had several jumping spiders mooching around the flat but this year I haven’t found one.
    I have found and ejected quite a few Pholcus Phalangioides which when small I call ghost spiders since they are difficult to spot. There seem a lot of them about this year.
    I have wondered if this has effected the jumping spider population or even the house spiders in general

    • Posted July 4, 2017 at 3:54 pm | Permalink

      The ‘cellar spiders’ will not deter jumping spiders. I have plenty of a related species, plus several species of jumpers around.

  5. Ken Pidcock
    Posted July 4, 2017 at 3:07 pm | Permalink

    Previously, I hadn’t known that cockroaches yell.

    • Diane G.
      Posted July 7, 2017 at 2:56 am | Permalink

      The sound effects on that last vid were a little much, IMO… 😉

  6. rickflick
    Posted July 4, 2017 at 3:12 pm | Permalink

    Portia. So much adaptability in such a small package. Her brain must be not much bigger than a sand grain. Maybe a couple of hundred neurons? Good God almighty! Beautiful creatures.

    I once had a statuesque female swim coach who wore a T shirt with: “All this and brains too!”. She was a student at MIT.

  7. Luke
    Posted July 4, 2017 at 5:49 pm | Permalink

    The ‘growling’ sound effects are hilarious!

    • Colin McLachlan
      Posted July 6, 2017 at 3:48 am | Permalink

      Yes, but finally very irritating. I found the entire sound track very overblown. There is enough drama there without turning it into a Godzilla movie.

  8. nicky
    Posted July 4, 2017 at 9:19 pm | Permalink

    That outflanking movement with the arial attack is really stunning.

  9. TJR
    Posted July 5, 2017 at 5:54 am | Permalink

    Portia spiders play a starring role in Adrian Tchaikovsky’s novel “Children of Time”. It reads like a collaboration between Richard Dawkins and Peter F Hamilton, so if that sounds like the sort of thing you’d enjoy then I guarantee you will.

    • darrelle
      Posted July 5, 2017 at 9:48 am | Permalink

      Thanks for the tip. I’ve added it to my list.

  10. Posted July 5, 2017 at 12:40 pm | Permalink

    Hats off to the photographers who take full advantage of their advanced cameras and telephoto techniques capturing so many wonderful pictures of fascinating animals!
    I also appreciate the internet, which makes it available to us, free and at almost no cost.
    .-


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