Fishes that have swim bladders can regulate their density and, thus, their buoyancy. There are two types of swim bladder: physostomous and physoclistous. The ancestral version is the physostomous version, in which the swim bladder is connected to the oesophagus via a short tube (see the figure). The fish fills this version by swimming to the surface, taking gulps of air, and directing them into the swim bladder. Air is removed from this version by "belching". The physoclistous version is more derived and has lost its connection to the oesophagus. Instead, gas enters and leaves the swim bladder via special circulatory mechanisms within the wall of the swim bladder.
-Which shark structure is closest in function to a swim bladder full of gas?
A) its lateral line system
B) its spiral valve
C) its liver
D) its gills

Question

Fishes that have swim bladders can regulate their density and, thus, their buoyancy. There are two types of swim bladder: physostomous and physoclistous. The ancestral version is the physostomous version, in which the swim bladder is connected to the oesophagus via a short tube (see the figure). The fish fills this version by swimming to the surface, taking gulps of air, and directing them into the swim bladder. Air is removed from this version by "belching". The physoclistous version is more derived and has lost its connection to the oesophagus. Instead, gas enters and leaves the swim bladder via special circulatory mechanisms within the wall of the swim bladder.
-Which shark structure is closest in function to a swim bladder full of gas?
A) its lateral line system 
B) its spiral valve 
C) its liver 
D) its gills

Quizplus · Accepted Answer

The liver of a shark is filled with oil that is less dense than water, which helps to regulate the shark's buoyancy in the water similarly to how a swim bladder full of gas helps other fish regulate their buoyancy.

Fishes That Have Swim Bladders Can Regulate Their Density And