The Acidic Fluttermud has gained the ability to inflate the pockets of air in its skin and fill them up with acid, as both an offensive and a defensive mechanism. Offensive as it can now prey on creatures that may have attacked it in its previous form, therefore not needing to hunt for as long, and defensive because any potential predators are less likely to attack it. If it's attacked whilst asleep - or even if it simply thinks it's in danger - then it instinctively squirts out jets of acid until the danger has passed.
