Answer:
A reaction to being spooked that takes its name from waterfowl
I am round as a bowl, deep as a tub, but all the world's water couldn't fill me up.
Which button does not function when being pressed?
A tiny bead, like fragile glass, strung along a cord of grass.
Metal or bone I may be, many teeth I have and always bared. Yet my bite harms no one. And ladies delight in my touch.
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?