gas exchange in insects

• Terrestrial insects


  • Have an exoskeleton made of chitin, a hard fibrous material
  • Contain a lipid layer to prevent water loss
  • Do not have lungs, instead have a tracheal system for gas exchange
• Tracheal system


  The gas exchange system in terrestrial insects
• Adaptations of terrestrial insects to reduce water loss

  • Small surface area to volume ratio of gas exchange system
  • Lipid layer on exoskeleton makes them waterproof
  • Spiracles can open and close to control water loss
• Tracheal system


  1. Spiracles

  2. Trachea

  3. Tracheoles
• Spiracles


  Round, valve-like openings along the insect's abdomen that can open and close to control water loss
• Trachea


  Internal tubes within the insect that have rings to keep them open and allow gas exchange
• Tracheoles


  The smallest branches of the tracheal system that reach every tissue in the insect
• Gas exchange in the tracheal system

  1. Diffusion

  2. Mass transport by muscle contraction and relaxation

  3. Fluid pressure changes due to anaerobic respiration
• The tracheal system provides a large surface area for gas exchange with a short diffusion distance, and the concentration gradient is maintained by respiring cells using oxygen and producing carbon dioxide