Fish ventilation

Question 1

Where is a fishes gill found and what is it protected and supported by?

Answer 1

Found in gill cavity.
Protected by operculum.
Supported by gill arch.

Question 2

What are gills made of?

Answer 2

• Many gill filaments (1^0 lamellae) -> large SA.

Question 3

What are gill filaments covered in?

Answer 3

• Tiny structures called gill lamella (gill plates) -> large SA.

Question 4

What happens when a fish opens its mouth?

Answer 4

• Increases volume and decreases pressure in buccal cavity -> water moves in.

Question 5

What happens when a fish closes its mouth?

Answer 5

• Decreases volume and increases pressure -> water leaves via the gills.

Question 6

How does fish ventilation work?

Answer 6

1) Mouth opens (operculum is closed).
2) Buccal cavity floor is lowered.
3) This increases volume and decreases pressure of the buccal cavity compared to outside.
4) Water rushes into mouth, down a pressure gradient.
5) Opercular cavity expands.
6) Buccal cavity floor is raised.
7) The pressure inside the buccal cavity is now higher than in the opercular cavity.
8) Water moves from buccal cavity over the gills into the opercular cavity.
9) Mouth is now closed and the operculum opens.
10) The sides of the opercular cavity move inwards, increasing the pressure.
11) Water rushes out of the fish, through the operculum.