1A hairlike structure that triggers a rapid movement when touched, in particular.
- ‘Electron micrographs of the active zone of the trigger hair reveal three regions in which the cells differ in size, shape, and cytoplasmic content.’
- ‘They are being observed by Major König who spies on them from an adjoining building and is waiting for the slightest glimpse of a human target in the trigger hairs of his sights.’
- ‘As a result, only one internal trigger hair stimulus is required to effect rapid trap closure.’
(in a coelenterate) a filament at the mouth of a nematocyst, triggering the emission of the stinging hair.
- ‘At the narrow outer edge of the cnidocyte is a short trigger hair.’
- ‘When the trigger hair on the outside of a nematocyte is touched, a coiled thread tube inside the enclosed nematocyst is released.’
A bristle on the leaf of a Venus flytrap, triggering the closure of the leaf around an insect.
- ‘Darwin's investigation into the biology of the Venus flytrap involved testing the sensitivity of trigger hairs.’
- ‘The flytrap features a set of inch-long, heart-shaped capture leaves, each fringed with trigger hairs and bisected by a deep fold.’
- ‘The trap does not close every time a trigger hair is touched because a lot of energy would be used up this way.’
- ‘The first phase of the leaf closure begins when a trigger hair is disturbed.’