STUDY VIII. VERTEBRATA. 



Central idea: The advantage of the "backbone" plan of 



structure. 



1. THE GOLDFISH AND PERCH. 



A. General Observations. 



1. What kind of symmetry does this fish possess ? 



2. Show by means of sketches the outline of the body 



of the fish as seen from above and from the side. 



3. Is the fish compressed or flattened ? 



4. Of what advantage to the fish is a body of this 



shape ? 



5. Of what advantage is it to the fish that the head is 



not movable independently of the body ? 



6. Count the number of paddle or fan-like appendages 

 (fins). Observe that some of the fins are median 



and that others are in pairs. 



B. Liocomotion. 



1. Is the fish an active or a sluggish animal ? 



2. Does it ever remain perfectly quiet ? 



3. Can it remain stationary without using its fins ? 



4. Can it go backward as well as forward ? 



5. Can it raise and lower itself in the water ? 



6. Identify and determine the use of the following fins, — 

 (a) the dorsal fin, the median fin on the dorsal surface ; 

 (J) the caudal fin, the fin forming the tail ; 



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