Let’s start with Portia, the genus of jumping spiders that prefers to eat other spiders. There are 17 of them in the genus, and as soon as they’re old enough to stray from their egg-sac they’re lean mean webbing-spider-eatin’ machines. When hunting, they carefully crawl into the other spider’s web and begin vibrating the strands to imitate a trapped insect. When the property owner comes to investigate what they think is probably lunch, Portia attacks, biting the other spider before it gets a chance to do the same to it.
Another interesting thing about Portia is their unusual intelligence (even for a jumping spider, which seem to be smarter than most anyway.) Lab studies have shown that they learn through trial-and-error, and they have been observed to find the best approach to a web, even if it means losing sight of the web in question as they circle to get to the best way in.
They also look like a piece of leaf detritus, something scientists believe camouflages them if they are spotted before they launch the attack on the other spider. A picture of one can be found here: http://en.wikipedia.org/wiki/Portia_(genus)#mediaviewer/File:Portia.fimbriata.female.-.tanikawa.jpg
Now, what about that vegetarian spider? Its name is Bagheera kiplingi, to use the scientific name. Perhaps “Bagheera” rings a bell. If so, that’s because it was named after the black panther in The Jungle Book by Rudyard Kipling. “Kiplingi” honors Kipling himself.
So, what do they eat? After all, there are many things that a spider that strays from the bug-eating stereotype could make do with. It turns out they eat something called Beltian bodies, nubs that form at the tip of branches on Vachellia trees. That’s the Latin name, and since we’re getting pretty heavy into the scientific names of things I wish the trees had common name I could tell you, but they don’t. Anyway, the Beltian bodies form as a symbiotic relationship with ants, and B. kiplingi avoids the angry ants to eat them.
Those nubs comprise over 90% of B. kiplingi’s diet, but the other 10% is filled with nectar and the occasional juicy ant larva. Pretty interesting, isn’t it? Who knew there was such a thing as an herbivorous spider? The truth is, no one did, until this species was described in 1896!
For now, this concludes my posts about jumping spiders. I hope you’ve enjoyed them!