Menacing crab spider with prey, focus-stacked
October 1, 2011
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I was very impressed with this spider, but then I really should stop being surprised by the ability of crab spiders to ambush and subdue large and potentially dangerous prey; I’ve encountered many flower crab spiders that have taken down bees or wasps twice their size.
This spider seemed particularly menacing for some reason. Legs spread wide, motionless, chelicerae buried deep, completely unbothered by the invasive camera lens – its prey utterly helpless.
Crab spider (possibly a ground grab spider, Xysticus sp.) with Camponotus prey
This photo represents my first attempt at what’s called a “focus stack”. It’s a post-processing technique where two or more photographs are essentially overlain in order to obtain a greater depth of focus. In this case, I had one photo where the spider’s face was in focus, and another where the ant was in focus (well, more or less). I stacked the two to get both in focus in this final image. Some people have perfected the art (think Thomas Shahan, from whom I learned about this technique at BugShot) and can manually stack five, six, seven or more frames to get the perfect photo with piles of depth, even when the magnification is really high. Here’s another great example from one of the others students who attended BugShot.