User blog comment:Plexioth- xD/Monster Hunter 3 Ultimate/@comment-6050823-20130123043000/@comment-5946566-20130125144628

^ Well, I have a theory. In my opinion, the Brachy's slime has some specific bacterias/microorganisms/things like that. When Brachydios hits with the "fists" or the horn, the impact causes the bacterias to become active and they provoke an specific reaction (for example, they produce an specific substance that reacts with the slime). Then, the slime becomes yellow and then red, because of the increasing of specific substance produced by these bacterias. When this substance is enough, it reacts producing an explosion. Also, as we all know the brachydios fists and horn become yellow when enraged, probabily because the bacterias become more active with brachydios' adrenaline and body heat, so they make the slime explode faster.