yadelah:

doctorbluesmanreturns:

bigwordsandsharpedges:

justthesource:

tilthat:

TIL that there’s a spider that is capable of insight, trial-and-error learning, and puzzle solving due its source of food: other spiders.

via ift.tt

source: https://en.wikipedia.org/wiki/Portia_(spider)

All spiders in the Portia genus are fascinating because of how much they accomplish with so little. They’re all tiny little jumping spiders, mostly under one centimeter, so they have tiny little brains.

Most Portia spiders have a brain of only 600,000 neurons, which is physically much smaller than the head of a pin. This forces them to think rather slowly from our point of view, but compared to their prey, they’re devastatingly brilliant.

For example, many jumping spiders are know to take detours when stalking prey. Portia spiders are notable for taking very long detours that break line of sight, which means they must remember and predict where the prey will be when they arrive.

When hunting sedentary web-building spiders, which usually have poor vision, a Portia spider will mimic a bit of leaf or bark to get into attack range. They only move forward during light breezes that shake the web enough to hide their footsteps. If the target moves to defend itself, Portia will disengage, retreat, and try again.

If they can’t get a good approach, they have also been recorded mimicking the vibrations of a trapped insect, or a male spider’s mating dance, to lure the prey spider into attack range. One Portia Fimbriata, the fringed jumping spider, was observed using trial and error to vibrate a target web for three days, repeating any pattern that caused the prey spider to move closer.

In places where other spiders aren’t common enough to be reliable prey, Portia adapts. They’ve been witnessed scavenging and even consuming nectar from flowers. They also innovate new tactics to hunt insects. For example, many insects freeze and stand motionless to avoid predators. Portia spiders counter this by guessing where the prey is and jumping nearby, which often scares the target into breaking cover and running. Then Portia can spot it and resume the normal detour-and-ambush routine.

The population native to Queensland, Australia is particularly inventive. They’re known to drop down on target spiders from above, a tactic called “swooping”. While all other Portia gladly jump into target spider webs, the Queensland orb weaver Argiope Appensa discourages them by shaking the web violently, which disrupts their normal techniques. Swooping counters this defense.

They also use a unique walking gait, slow and robotic, when hunting other saltacid jumping spiders with large forward-facing eyes. They freeze and depend on their natural camouflage whenever the target looks directly at them, so we suspect they prey may not even recognize them as living creatures. Portia rarely uses this “cryptic stalking” technique against any other prey.

Portia Africanus appeared to be a comparatively bad hunter at first glance, but that was in lab testing with 1v1 combat. In the wild, this spider hunts in packs.

Yes, really. They form social groups that hunt cooperatively and sometimes share prey. Groups of mixed ages and sexes will gang up outside the nest of a target spider. They prevent the target from entering or leaving and surround them until one of the Portia, usually a juvenile, manages to lunge forward and bite.

@msburgundy

I don’t know why but this makes me think about that one post that’s like “if the uncanny valley was a defense mechanism then what exactly were we hunted by for so long that that evolved?”