Definition of trigger hair in English:

trigger hair

noun

  • 1Zoology
    (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.’
  • 2Botany
    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.’