recently I found that whenever I touch my turtle face(near the mouth area when his body is dry) he would open his mouth way wide, but he's not trying to bite me or anything, or maybe he's trying to scare me away? but I remember my turtle never used to do that, he always let me pet him under the chin, but now he just opens his mouth so wide and I couldn't touch him anymore

, do they go through mood changes?
Also, this is amazing, but when my turtle opens his mouth, I saw this 'place' opens up right behind his tongue and then close back up again, it's almost like another opening, is that where he swallow his food? or is this the place to hold the food in place? it's very much like a scene from "alien", where there's a mouth inside the mouth