Scorpions are known to fluoresce in 465 nM UV light.  Here are images of a mom with a zillion juvenile scorpions hanging on.  The mom fluoresces brightly and the kids do not fluoresce at all.  These is some indication that the protein associated with fluorescence is not expressed until several molts have occured
<a href="//commons.wikimedia.org/w/index.php?title=User:Frank.starmer&amp;action=edit&amp;redlink=1" class="new" title="User:Frank.starmer (page does not exist)">Frank.starmer</a>
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<span class="int-own-work" lang="en">Own work</span>