Gas Exchange - Bony Fish

Question 1

What is the structure of the gas exchange system in bony fish?

Answer 1

Operculum protects gills.

Gills on each side of head

Gillarch has two stacks of filaments with lamellae.

Capillaries surround the lamallae.

Question 2

How do fish maintain a current of water?

Answer 2

Takes in water through the mouth and forces it through its gill slit which maintains a concentration gradient and water flows out through the operculum.

Question 3

What are the lamellae?

Answer 3

The surface is a single layer of flattened cells next to a network of capillaries, which are close to the surface so oxygen has a short diffusion distance.

Question 4

How does water move into the mouth?

Answer 4

Mouth opens
Operculum closes
Floor of mouth lowered
Volume inside buccal cavity increases, pressure decreases
Water flows into buccal cavity.

Question 5

How does water move out of the mouth?

Answer 5

Mouth closes
Floor of mouth raised
Volume of buccal cavity descreases, pressure increases
Operculum opens
Water flows over gills into opercular cavity and out

Question 6

What is the parallel flow system (in sharks- NOT BONY FISH)?

Answer 6

The water flows in the same direction of the blood.

Question 7

How does water flow in a bony fish?

Answer 7

Diffusion can occur across the entire gill lamella because O2 concentration in H2O is always higher than in the blood.