These awesome spiders each have their own personal mirror balls. They’re disco spooders! Actually they’re called Mirror or Sequin spiders (Thwaitesia sp.) and Singapore-based macro photographer Nicky Bay (previously featured here) has been studying them for the last several years.
Bay noticed that the spiders are able the change the size of the reflective silver patches of guanine on their abdomens when they feel threatened:
“For several years, I have been observing the odd behavior of the Mirror Spider (Thwaitesia sp.) where the “silver-plates” on the abdomen seem to shrink when the spider is agitated (or perhaps threatened), revealing the actual abdomen. At rest, the silver plates expand and the spaces between the plates close up to become an almost uniform reflective surface. That is why I called it the Mirror Spider. Note that what I am posting are just field observations and not based on scientific literature.”