  In this review, we discuss the use of time-of-flight secondary-ion mass
spectrometry (TOF-SIMS) technology for analyzing the viscous glue (is called
aggregate glue droplets) of spider orb webs and examine the results obtained.
Element distribution images of the aggregate glue droplets were observed by
TOF-SIMS. A uniform element distribution is seen for suspended pristine
aggregate glue droplets, and a differential spreading of aggregate glue
components is seen for attached aggregate glue droplets. We also observed
TOF-SIMS images of water in aggregate glue droplets, where water was observed
to be consistent with the distribution of oozing salt. We also found that the
alkali metal in the aggregate glue droplets showed similar characteristics by
feeding cesium carbonate to spiders.
