BONY FISH gas exchange

• Why have bony fish evolved a specialized gas exchange system?

  To extract maximum oxygen from water
• What is the skeleton of bony fish made of?

  Bone
• What is a significant issue bony fish face regarding gas exchange?

  They have a low surface area to volume ratio
• Name three examples of bony fish.

  Tuna, salmon, and cod
• How do bony fish obtain oxygen?

  From the water they swim in
• What is the role of the operculum in bony fish?

  It covers the gills and aids in water flow
• What happens to oxygen in the gills of bony fish?

  It diffuses from water into the blood
• What are gill lamellae and their function?

  They are structures where gas exchange occurs
• How are gill lamellae adapted for gas exchange?

  They have a large surface area and short diffusion distance
• What maintains a steep concentration gradient for oxygen in bony fish?

  The extensive network of blood capillaries
• What is a counter current exchange system?

  Blood and water flow in opposite directions
• What is the advantage of a counter current system in bony fish?

  It maintains a steep concentration gradient for oxygen
• How much oxygen can diffuse into the blood with parallel flow?

  No more than 50 percent of available oxygen
• How much oxygen can diffuse into the blood with counter current flow?

  Up to around 80 percent of oxygen
• How do bony fish maintain constant water flow through their gas exchange system?

  By using a buccal cavity mechanism
• What happens when a bony fish opens its mouth?

  Water flows into the buccal cavity
• What occurs when the operculum is shut?

  The volume of the opercular cavity increases
• What happens to the pressure in the opercular cavity when its volume increases?

  The pressure falls, allowing water flow
• What happens when the fish closes its mouth and opens the operculum?

  Water is forced out of the operculum
• How do the sides of the opercular cavity affect water flow?

  They squeeze inwards, increasing water pressure
• What are the main components of the gas exchange system in bony fish?

  • Operculum
  • Opercular cavity
  • Gills
  • Gill arches
  • Gill filaments
  • Gill lamellae
• Describe the process of water flow in bony fish.

  1. Mouth opens, water enters buccal cavity
  2. Volume of buccal cavity increases, pressure drops
  3. Operculum shuts, volume of opercular cavity increases
  4. Pressure in opercular cavity falls, water flows over gills
  5. Mouth closes, operculum opens, water is forced out