From wiki:<quoted text>Very good site and a lot of information there about the Bombardier Beetle. I hope that you read the evolution of the defense system. Because all it does is explain how the defense system operates. It doesnÂt explain how this creature evolved nor how itÂs chemical weapon defense evolved.
It only eludes to exaptation, which is a, maybe, sort of, could have scenario. A weak counter argument based on speculation.
When a bombardier beetle is threatened by a predator or an offensive invader of any kind, at the appropriate point of approach, the bombardier beetle swings its tail end around, and hot, noxious fluid heated to 100 Â°C (212 Â°F) is explosively released from twin combustion tubes into the face of the enemy. Various quinones are commonly produced by cells in the skin of insects to harden their skin into a cuticle, and as they taste bad to predators, many insects secrete them to deter predators. Where there are indentations in the cuticle, these vary to form little sacs that store the deterrent quinone. Where predators develop resistance to this chemical, other related chemicals such as hydroquinone develop, and in many beetles, specialised cells secrete hydroquinone from glands connected by ducts to a reservoir sac, which can be closed off by muscles to stop leakage.