You know what’s exciting? This is my 200th post on Our Wild World. To celebrate, I put myself through hell to try and find a super amazingly cool spider species to blog about. This involved sifting through lists of spiders on the internet, something that made me extremely jumpy for the rest of the day.
The spiders I settled on (and it was a tough choice, believe me) are Portia spiders. These spiders don’t build crazy webs, they aren’t extremely large or hairy, they aren’t particularly venomous, and they don’t live in strange or wonderful places. You see the trait that makes Portia spiders so special is one I value above all others: intelligence.
Though I don’t usually associate intelligence with invertebrates, it seems that Portias are quite clever. They mostly use their quick wits to hunt, and guess what they hunt? Other spiders! Which moves Portia way up on my list of favourite spiders.
Portia is actually a genus of jumping spiders, comprised of 17 species. They range from Africa to East Asia and Australia. They live in tropical rainforests, places where there are lots of other spiders for them to eat.
Portia spiders do look pretty weird — their long legs and hair are meant to make them look as little like a spider as possible. This is a key element in their hunting techniques. I say hunting techniques because Portia doesn’t just use one style of hunting. They use different methods of stalking prey depending on what they’re hunting, and they can learn new tricks all the time. Using their smarts, Portia spiders can capture spiders 200% bigger than themselves. Not too shabby.
One of Portias favourite methods of hunting involves building a web attached to their prey’s web. They sit in their little web add-on and stalk their prey. To web-building spiders, who have terrible eyesight, Portias look like a bit of debris caught in their web, so the Portia spiders can easily surprise their prey. But Portia spiders are far too impatient to just sit there and wait for their prey to wander over. Instead the crafty little spiders pluck strings of their prey’s web, imitating the struggles of a bug caught in the web. This brings the prey spider scuttling on over, which leads to a swift attack from the Portia spider. If the Portia’s web manages to catch an insect by accident, the spider will usually leave the insect struggling, so it will attract Portia’s real prey — the web-building spider.
Portia spiders are not so remarkable because they lure prey in and stalk them; anyone can do that. But Portias can adapt to different situations and different prey, learning the best way to hunt varied species. For example, if an approaching web spider acts aggressively towards a Portia spider, the Portia spider will retreat, and approach from a different angle, often hanging down from a thread to attack from above. This often results in the Portia spider losing visual contact with its prey, sometimes for up to an hour. Which means that these spiders have an incredible memory for such a small and basic nervous system.
Spitting spiders are another tricky prey item — they spit venomous webbing onto their prey (which happens to be jumping spiders), so Portia spiders hunt these guys from behind. If the spitting spider is carrying an egg sack, on the other hand, it cannot spit, and so the Portia spider will attack from the front. Portiass learn very quickly in laboratory settings how to deal with web-building spiders that they’ve never encountered and that their ancestors would never have met. They will even time their movements on other spiders’ webs to coincide with breezes, so their vibrations are masked.
Spider intelligence may seem like an oxymoron — it’s generally believed that most invertebrates are not sentient and thus cannot have intelligence, but I still think the Portia spider is pretty impressive. And who knows, as more research emerges and we get better at measuring consciousness, we may discover that we’ve vastly underestimated the mental abilities of the animals around us.
Cover image source: http://zombiechops.com/freature-the-portia-spider/