Gas Exchange in Fish

Question 1

What are fish made up of ?

Answer 1

• Bony fish are made up of skeletons made up of bones

Question 2

What is the circulatory system of fish ?

Answer 2

• Single, closed circulatory system
• Ventricles pump blood to gills where gas exhange occurs

Question 3

What is the operculum ?

Answer 3

• A flap in front of the gills

Question 4

What is the function of the operculum ?

Answer 4

• CLOSED - provides protection of gills when closed
• OPEN - maintains constant water flow over gills

Question 5

What are the gills ?

Answer 5

Bony fish have four pairs of gills, each gill supported by an arch. Along each arch there are multiple projections called gill filaments, with lamellae on them which participate in gas exchange.

Question 6

What is counter current flow ?

Answer 6

-Blood and water flow across the lamellae in a counter current direction meaning they flow in opposite direction.

Question 7

Explain ventilation in bony fish

Answer 7

• Fish opens buccal cavity - lowers buccal cavity floor
• This decreases the pressure in the buccal cavity but increases pressure on the outside
• As a result the water flows into the pressure gradient into the buccal cavity , causing the operculum to close
• Fish raises floor of buccal cavity and closes it mouth
• Causing the pressure inside the bc to increase compared to the outside
• Finally water flows to the pressure gradient through gills and opens the operculum relasing the water out of the fish

Question 8

What are adaptations that ensure efficent gas exchange ?

Answer 8

• Counter current flow- Blood and water flow across the lamellae in a counter current direction meaning they flow in opposite direction and create a steep concentration gradient for oxygen and carbon dioxide
• Contain a large number of gills, capilliries,lamellae and gill fillaments inrecases surface area for the diffusion of oxygen and carbon dioxide.