Figure 27.2 Fishes That Have Swim Bladders Can Regulate Their Density and Density

Figure 27.2
Fishes that have swim bladders can regulate their density and thus their buoyancy. There are two types of swim bladder: physostomus and physoclistus. The ancestral version is the physostomus version, in which the swim bladder is connected to the esophagus via a short tube (Figure 27.2) . 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 physoclistus version is more derived, and has lost its connection to the esophagus. Instead, gas enters and leaves the swim bladder via special circulatory mechanisms within the wall of the swim bladder.
-Rank the following fish, from most to least, in terms of the amount of energy each must use to maintain its position (depth) in the water column over the long term. 1. physoclistus fish
2) physostomus fish
3) chondrichthyan fish

A) 1, 2, 3
B) 2, 3, 1
C) 2, 1, 3
D) 3, 1, 2
E) 3, 2, 1