Electrical Communication in the Venus Flytrap (Cambridge (CIE) A Level Biology) : Revision Note

Electrical communication in the Venus flytrap

• The Venus flytrap (Dionaea muscipula) is a carnivorous plant that can gain nitrogen compounds by trapping and digesting small animals, mainly insects

• The specialised leaf is divided into two lobes on either side of a midrib

  • The inside of the lobes is red and has nectar-secreting glands on the edges to attract insects

• Each lobe has three stiff sensory hairs that detect touch

• If an insect touches one of these hairs, action potentials are generated

• These action potentials cause the two lobes to fold together along the midrib, capturing the insect

The Venus flytrap has specialised features that enable it to catch and digest insects

How the closure of the trap is achieved

• The closure of the leaves occurs when the sensory hairs are touched repeatedly, generating an action potential as follows:

  1. an insect lands on the leaf and touches the sensory hairs

  2. calcium ion channels in cells at the base of the hair open

  3. calcium ions flow in and generate a receptor potential

  4. if two of the sensory hairs are stimulated at the same time, or one hair is stimulated twice within around 30 seconds, an action potential occurs and is propagated across the cells of the trap

     • If repeat stimulation does not occur then the trap resets and the process needs to start again from the beginning; this ensures that the plant does not waste energy by closing when an insect is not present

  5. the cells at the base of the trap change shape, and the trap closes

     • Sealing the trap requires ongoing activation of the sensory hairs, which occurs when the prey continues to move around inside the closed trap

  6. further stimulation of the sensory hairs causes calcium ions to enter gland cells where they stimulate the exocytosis of vesicles containing digestive enzymes

  7. the trap then stays closed for up to a week to allow the prey to be digested and the nutrients from it to be absorbed by the plant