Where are the mermaids?

I just saw my first out of disguide merman. It may be a coincidence, but I was playing a CAS-created merman when it happened.

Mine was disguided, but the townie merman was swimming around in full view, true form exposed and all. Asked about being a merman the townie denied it. So half an hour later when he went into the water my merman followed him and summoned a Terror of the Deep on his lying backside. Poor guy went back to the shore immediately afterwards, where he kept standing like a pillar of salt, probably going What just happened?!