196 BIOLOGICAL RELATIONS OF AQUATIC FORMS 



4. What adaptations that you have studied fit a fish for life 

 in water? Explain. 



5. Tell just how any one fin or set of fins is adapted or fitted 

 to do its work. 



b. Adaptations for Respiration 



Observations. 1. What movements of the mouth do you 

 observe ? 



Note. As the fish closes its mouth, note the movements of 

 the operculum, or bony flaps just in front of the slits on the 

 side of the " neck " region. 



2. Does the operculum open or close as the fish closes its 

 mouth ? 



3. Do you see red gills underneath the operculum ? 



4. Pour water from a height into the battery jar or aquarium. 

 What is carried into the water ? 



Conclusions. 1. How can you temporarily aerate an aqua- 

 rium ? 



2. How could a fish be suffocated without taking it out of 

 water ? 



3. What precautions should be observed in keeping fish in 

 aquaria ? 



4. Mention at least two respects in which fishes are adapted 

 to lead an aquatic life. 



5. Why should the operculum open as the mouth closes ? 



6. Tell just how a fish breathes. 



7. Why should a fish breathe ? 



c. Sense Organs 



Observations. 1. What movements of the eyes do you 

 notice ? 



2. How large a range of vision has it (number of degrees) ? 



3. Can a fish close its eyes? 



4. Note. Look at the skeleton of a fish, and note the deep 

 cavity (orbit) in which the eyes are set. 



