The sincerest form of flattery

I’ve been quiet for a few days, which is a good sign in field work: many new specimens to process will keep me away from the computer. To break the silence I’ll show two ants, which despite Heather’s gasteropost and subsequent comments, have a certain cuteness to them. But of more interest to me than the two ants (sorry, myrmecologists) are some jumping spiders that look a whole lot like the ants.

cephalotineIMGP9684
First is a cephalotine ant, which I find rather stylish with its grey robotic body. Below are a Bellota and a Peckhamia, both of which have independently evolved a resemblance to it.

BellotaIMGP9682
Bellota. I like how the head of the spider seems to correspond with the thorax of the ant, with the thickened first legs of the spider corresponding with the head of the ant.  (Why the spider’s name comes from the Spanish word for “acorn”, I don’t know.)

PeckhamiaIMGP9559
Peckhamia. While many antlike jumping spiders wave around the first legs as if they were the antennae of their model ants, Peckhamia belongs to a group that waves around its second pair of legs.

PseudomyrmexIMGP9858
The second ant is a Pseudomyrmex, the long, thin, quick ants common here in Jalisco.

SynemosynaIMGP9023
And this is not an ant but Synemosyna. Even after decades of looking at jumping spiders, when I find a Synemosyna I have to look closely to confirm that it’s actually a spider. This particular species has black spots corresponding to the eyes of ant — within the black spot is one of the spider’s eyes, but the eye is much smaller than the spot.

Why is it a good idea for a jumping spider to look like an ant? This hasn’t been well enough studied to answer the question with confidence. For most antlike jumping spiders, the mimicry does not seem to have evolved to fool the ant (e.g. to eat the ants, like a wolf in sheep’s clothing). One possibility is that it’s a good idea to make a predator think you are an ant, as many predators avoid ants because they can sting or bite and are accompanied by many friends who will do the same. Check out Heather’s blog for some insects that have evolved to look like ants.

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