FISHERY BULLETIN: VOL. 70, NO. 4 



20 cm away, its forward motion almost ceased. 

 Then, when within 3 to 5 cm of the prey (Figure 

 5C), the fish beat downward with the caudal fin 

 and with mouth agape and opercula spread, 

 moved forward and downward. As the fish in- 

 gested the shrimp, it would usually make contact 

 with the bottom with its snout, then glance off 

 the sand, and move slightly forward and upward 

 (Figure 5D) . The fish would then resume swim- 

 ming or settle on the sand. 



The basic elements of prey selection and visual 

 fixation were essentially the same whether the 

 fish were feeding in the water column or on the 

 bottom. While the flounder were actively swim- 

 ming or gliding toward shrimp, they would ap- 

 proach and decrease speed by raising posterior 

 portions of the dorsal and anal fins and arching 

 the body into a partially flexed position. Then, 

 with a rapid caudal flexion, the fish would cap- 



ture and ingest the shrimp. As was the case 

 with bottom feeding, after capturing a prey, a 

 fish would either continue active search or settle 

 on the sand. 



The searching, stalking, active eye move- 

 ments, and visual fixation on specific prey all 

 indicated that vision was a primary sense used 

 in feeding during the day. We observed feeding 

 at night, and while it appeared to us that the role 

 of vision was similar to that in the day, we could 

 not preclude the possibility of other senses play- 

 ing more dominant roles. 



At times the flounder would approach a prey, 

 as if to begin stalking or a capture, but would 

 then turn away. We considered this tjrpe of be- 

 havior to be a feeding intention movement. For 

 example, a flounder would swim toward shrimp 

 on or near the bottom, assume a prestrike pos- 

 ture, visually fix on a shrimp, and open and close 



Figure 4. — Prey capture following stalking. The fish assumes a position prior to striking. 

 The body is slightly raised off the sand and the eyes are visually fixed on the prey (A). 

 As the strike begins, the caudal fin beats downward (B), thrusting the fish forward for 

 the capture (C). 



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