Because he doesn't look to be over 31" or 24" for that matter. But then again it is hard to judge accurate lengths in a photograph and I'm assuming that that is a 16oz deli cup next to him, which has a 4" diameter. If he is that big that is very impressive. Our largest gila is a 21" female that weighed 1243g as she was being put into cold storage last month. I always thought that she was a BEAST because I had never seen one her size so I can't even imagine an additional 10" on top of that let alone the 36" that this person claims. WOW.