User blog comment:IamJakuhoRaikoben/Chapter 474: In the Moment of Complete Silence, Review./@comment-4449950-20160222214714/@comment-5303512-20160222220611

I think that with Juvia's water body, it doesn't work like OP Logia users where it is alway active, she like Ajeel have to be aware of the attack coming for them to activate their elemental bodies. Or if there are other mages with powers that can counter those elemental bodies.