Internal fish anatomy - swim bladder

Question 1

Where is the swim bladder in most bony fish?

Answer 1

• below the backbone

Question 2

What is the swim bladder similar to?

Answer 2

• bag-like organ filled with gas controlled by blood

Question 3

What does the swim bladder serve for in lungfish?

Answer 3

• serves as an air-breathing lung

Question 4

What do some catfish use the swim bladder as?

Answer 4

• used to produce sound as well as providing buoyancy (the ability or tendency of something to float in water or other fluid)

Question 5

What happens with the water pressure if a fish swim deeper?

Answer 5

• water pressure increases
• the pressure of the water reducing the size of the swim bladder, therefore reducing buoyancy

Question 6

What does the nervous system of a fish do?

Answer 6

• automatically regulates the amount of gas in the bladder so that it is kept properly fitted

Question 7

Do sharks or rays have a swim bladder?

Answer 7

• no they do not
• to maintain their buoyancy they have to swim constantly

Question 8

What happens when sharks or rays rest?

Answer 8

• they stop swimming therefore they will sink towards the bottom
• Many bottom-dwelling bony fish also lack a swim bladder