User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-5089728-20120926040336/@comment-4212769-20120926104708

Most monsters are almost perfectly adapted to living in nearness of lava or in lava. Most monsters have a much thicker skin to live in the heat. Also I guess they have a higher body temperature to have less effort to cool their body down.

Agnaktor has also a thicker skin but as it uses a fire beam its mouth and throat needs to be very fire resistant, too. That's why it doesn't hurt it much when lava gets in its mouth. Its eyes get probably protected by some kind of nictitating membrane or/and a thicker Cornea. So it can live in lava with open eyes and mouth.

And even if the lava on it's body hardens they still have a hold on it as the body and environmental temperature can still keep the lava on the skin liquid.

A hunter has the heat protection of his/her armor and the cold drink that seems to have a rather big effect.

P.S.: If you/we don't have a reason why lava could be cooler there I don't think it's scientifically worth to come with that unless we have actual temperatures of it.