Gas exchange in fish

• where does gas exchange take place in fish?

  it takes place across a special respiratory surface - the gill
• what do gills have?

  • a one-way current of water, kept flowing by a specialised ventilation mechanism
  • many folds, providing a large surface area over which water can flow, and over which gases can be exchanged
  • a large surface area, maintained as the density of water flowing through prevents the gills from collapsing on top of each other
• what are the 2 main group of fish?

  • cartilaginous fish
  • bony fish
• whats the difference between cartilaginous fish and bony fish?

  the cartilaginous fish have a skeleton of cartilage and the bony fish have a skeleton of bone - they ventilate their gills in different ways