How do ray-finned fish keep from sinking?
A)they are constantly swimming
B)their fins are constantly moving
C)they have lungs that are always filled with air
D)they have a swim bladder that is filled with gas
E)they have a skeleton that is less dense than the surrounding water

Question

How do ray-finned fish keep from sinking?  
A)they are constantly swimming
B)their fins are constantly moving
C)they have lungs that are always filled with air
D)they have a swim bladder that is filled with gas
E)they have a skeleton that is less dense than the surrounding water

Quizplus · Accepted Answer

Ray-finned fish have a swim bladder, which is an internal gas-filled organ that allows them to control their buoyancy and stay afloat. They can adjust the amount of gas in the swim bladder to change their depth in the water.

How Do Ray-Finned Fish Keep from Sinking