Meet Peckhamia, a charmingly ant-like jumping spider:
Peckhamia avoids being eaten by predators by appearing like an ant rather than a spider. This defense is two-fold. Ants aren’t as palatable as spiders to most general predators, and spider-specialized predators might not recognize Peckhamia as food.
For mimicry to work optimally, though, spiders must inhabit places with plenty of ants. Not the easiest task, since ants eat spiders. And because most ants have poor vision, the spider’s physical resemblance to ants isn’t much help.
So how does this ant mimic spider escape being attacking by ants?
A new paper by Divya Uma et al in PLoS One provides a partial answer: Peckhamia doesn’t smell like a jumping spider. It doesn’t smell like an ant, either, so it’s not a chemical ant mimic. In fact, Peckhamia doesn’t smell like much at all. Look at the results of Uma et al’s cuticular hydrocarbon assay:
Cuticular hydrocarbons are chemicals that impart odor, and Peckhamia has rather low amounts of these. It’s a stealth spider!
The researchers also measured predation rates by spider-eating wasps on Peckhamia (lower than on related species), and rates of attack by ants (lower against mimic spiders than against non-nestmate ants). I’d have liked to see the next step of actually painting hydrocarbons on the mimics to gauge the ants’ reaction, but even without that experiment the odorlessness of Peckhamia is an intriguing observation.
[for more ant mimics, see my ant mimic photo gallery]
source: Uma D, Durkee C, Herzner G, Weiss M (2013) Double Deception: Ant-Mimicking Spiders Elude Both Visually- and Chemically-Oriented Predators. PLoS ONE 8(11): e79660. doi:10.1371/journal.pone.0079660