CHEMORECEPTION: LOCOMOTION AND ORIENTATION 



309 



T3 



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0) 



u 

 c 

 o 



80 - 



70 



60 



50 



40 



30 



20 



Quadrant I 



Quadrant 2 



Quadrant 4 

 Quadrant 3 



Site of Chemical Stimulation 



Figure 27 Ginglymostoma cirratum: regressions of the percentage of distance 

 traveled in each of the quadrants of the monitor, as a function of the position 

 of the needle releasing the chemical stimulation. Conditions were as in Fig. 25, 

 but the water was stagnant. From Kleerekoper et al. (1975). 



to the conclusion that the strength of the chemical gradient is important in 

 determining the nature of the locomotor response and the accuracy in local- 

 izing the source of a chemical stimulus. 



The mechanism for localizing the stimulus source is different in flowing 

 and in stagnant water, as can be inferred from the turning behavior of the 

 shark in the course of orienting toward the stimulus source in the two 

 conditions (Figures 29a, b). The relationship between turning frequency and 

 position of release site actually reverses with stimulation at site 1 and quad- 

 rant 1 as flow conditions change. In conditions of flow, relatively few turns 

 are made, whereas in the absence of flow, almost 41% of all turns are made 

 there. 



