Question

select the correct answer.
while gutting a fish, nathan encountered an air - filled sac - like structure. what is the purpose of this structure in fish?
a. it enables fish to breathe in water.
b. it serves as a reserve space to store fat.
c. it harbors bacteria that benefit the fish.
d. it provides buoyancy to the fish.

Explanation:

The air - filled sac - like structure is the swim bladder. The swim bladder helps fish maintain buoyancy. Gills enable fish to breathe in water (so A is wrong). It is not for storing fat (B is wrong) or harboring bacteria (C is wrong).

Answer:

D. It provides buoyancy to the fish.