Part of me is tempted to go back and see if there were any previous episodes in which we saw an animal with a defined navel, just to see if the animators had been keeping this detail in mind from the beginning. I'm not going to, that would be a lot of effort over something that just isn't that big a deal one way or the other. The important part is that it would appear that Buki's dad is on to Tarte's identity as a fairy and responded in a completely reasonable fashion.
Also, why was the net monster Mexican? That...just stuck out as random to me.