FISHERY BULLETIN: VOL. 77. NO. 4 



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Figure 5. — Spinner dolphin reenter- 

 ing the water after a spin, seen from 

 below. Note the longitudinal hollow of 

 water scooped out by the rotating ani- 

 mal. Photo by Henry Groskinsky, cour- 

 tesy Time, Inc. 



Figure 6. — Body postures of spinner dolphins during a spin Vertical and horizontal dimensions of leap not to scale. Redrawn from 



Hester etal. (1963). 



ous of our presence. The last spin launched the 

 animal nearly at the bow; it fell back into the 

 ship's bow wave, startled, and swam rapidly away 

 below the surface. 



Spins may be seen in all parts of a school. Lead- 

 ership or dominance do not seem to be the obvious 

 factors in spinning behavior. In fact, the opposite 

 could be true since very young animals spin, and 



in our observations of captive spinner dolphins a 

 high frequency of spinning was observed in an 

 animal that had not been socially accepted into the 

 resident captive school. The best correlation of 

 frequency of spinning and the condition of a school 

 seem to relate to alertness, or activity level of the 

 animals involved, the greater the alertness the 

 more frequent the spins. The more spread out a 



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