Palpimanoid Spiders
 
Hannah Marie Wood
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New Zealand
March 18 - March 27, 2011
 
Lewis Pass
   I went back to New Zealand in order to collect palpimanoid spiders. While I knew that some Chilean mecysmaucheniids had evolved a high-speed trap-jaw mechanism, I was not sure about the behaviors of the New Zealand species. I was also interested in the jaw mechanisms of pararchaeid spiders, which have convergently evolved the "neck" morphology. I suspected that pararchaeids had extremely rapid movements, whereas the New Zealand mecysmaucheniids would have slower jaw movements. It turned out to be the opposite: while both families of spiders have trap-jaw behaviors, the pararchaeid jaw movements were still in the range of what what possible with muscle, however, the New Zealand mecysmaucheniids turned out to be the fastest known lineage so far. The high speed camera was not fast enough to capture their jaw movements, which occurred in less than two frames when the camera was recording at 40,000 frames per second. At this time and until these spiders are examined with a faster high speed camera, we do not know the jaw closing speeds of these spiders. The photo above is Lewis Pass, where I spent most of my time collecting on this trip.
   

An x-ray image of the carapace and jaws of a New Zealand trap-jaw mecysmaucheniid, lateral view, taken at the Advanced Light Source synchrotron. These are so far the fastest known trap-jaw spiders, and also the smallest, with the length of the carapace being less than 0.7 of a millimeter!

Anterior view of the same specimen, note the thick bundles of tissue connected at the front of the jaws - these seem to store energy when the jaws are stretched opened, which is released when the jaws are released, causing extremely high-speed jaw movements.
     

Nothofagus trees at Lewis Pass - mecysmaucheniid trap-jaw spider habitat.
 

A mushroom at Lewis Pass, NZ.
 

Side trip to Abel Tasman National Park.