Ventilation and gas exchange - Insects

• Spiracles - Small holes along the thorax and abdomen:

  • Air enters and leaves
  • Water is lost
  • Controlled by sphincters
• Tracheae - Tubes that carry air into the body:

  • Lined with chitin - Strong and keeps tracheae open
  • Impermeable to gases - Little gas exchange
• Tracheoles - Narrower tubes than tracheae:

  • Freely permeable to gases - No chitin lining
  • In-between tissues - Small sizes
  • Large surface area - Efficient gas exchange
• Tracheal fluid - Protects the tracheal system from dehydration and mechanical damage
• Gaseous exchange system in an insect

  A) tracheoles

  B) tracheae

  C) spiracle