Insects

• Insects are adapted to reduce water loss

  • exchange system have small surface area to volume ratio
  • waterproof cuticle covering their exoskeleton
• When insects are in flight

  • Tracheoles fill with water
  • Muscles respire anaerobically partially and produce lactate
  • Water potential in cells lowered
  • Water moves via osmosis from tracheole into cell
  • Air drawn into space vacated by water
  • Increases rate of diffusion
• Spiracles trap water molecules around the opening to maintain the higher water concentration
• Spiracle openings occur at a lower frequency in dry conditions