BARHAM, GOWDY, and WOLFSON: ACANTHASTER IN GULF OF CALIFORNIA 



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Figure 5. — Acant hosier ellisii, specimen no. 1, photographed while moving over a large rock in the 

 Pink Cliff study area. The tag is tied to the proximal part of the arm nearest the camera. 



plastic PVC (polyvinyl chloride) pipe weighted 

 with lead strips to stand vertically. Small sur- 

 face buoys equipped with life-jacket lights were 

 anchored near each location to aid in night 

 operations. 



Observation and search periods are given in 

 Table 3. Time on the bottom was dependent on 

 our scuba air supply. The greatest care was 

 taken to minimize disturbance of the animals. 

 Specimens on the move were not touched and, 

 to prevent interruption of their activity by 

 stimulating the "shadow reflex" (Hyman, 1955), 

 we tried to avoid swimming over them. The 

 activity of animals at rest was investigated by 

 gently lifting a part of the body with a knife 



blade. Distance of movement was measured with 

 a meter stick; direction was determined by com- 

 pass bearings. Following each observation, 

 the pipes and buoy anchors were transferred to 

 the new position. 



Specimens in the open were recovered with 

 relative ease; locating them on the rock pile or 

 in its interstices was difficult or even impossible, 

 especially at night. During the course of the 

 study, we failed to recover individuals on six 

 occasions. Three times the "lost" specimen 

 was found on the succeeding search; we suspect 

 that no. 1 and 2 specimens, which were last 

 seen close to their original position (see Figure 

 2), had moved out of the search area. 



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