HOBSON: CLEANING SYMBIOSIS 



Figure 4. — Senorita cleaning the caudal peduncle of one of a group of blacksmiths that 



hover to solicit service. 



though it is beginning to assume a soliciting 

 posture; however, when the seiiorita swims on 

 past, the blacksmith immediately resumes its 

 original activity. Occasionally members of other 

 species were seen responding similarly to passing 

 seiioritas. In most observations of cleaning, my 

 attention was drawn to activity already in prog- 

 ress, so that it was not possible to determine 

 whether cleaner or client had initiated the ac- 

 tivity. 



Individual seiioritas that cleaned blacksmiths 

 during many short-term observations were not 

 seen cleaning any other species. This same 

 situation held true for three individuals, known 

 to have been cleaning blacksmiths, whose ac- 

 tivity was monitored in detail on tape for 15 

 min. When observed for extended periods, 

 seiioritas were found to become involved in 

 a succession of separate cleaning bouts. This 

 activity was not restricted to one location but 

 continued at various points over a relatively 

 wide area. Periodically they joined cleaning al- 

 ready underway, or initiated cleaning themselves 



at a number of different locations — always with 

 blacksmiths. I have no explanation for the fact 

 that a sefiorita which becomes unresponsive and 

 leaves one group of blacksmiths that still vigor- 

 ously solicits its service may soon initiate ac- 

 tivity again with another blacksmith. 



The three individuals whose cleaning activity 

 was monitored for 15 min joined in a mean of 

 4 separate bouts (range 2-6) . For a mean of 11 

 min of this time (range 6.75-13.25 min) they 

 showed an apparent cleaning interest in black- 

 smiths, or were accompanied by blacksmiths with 

 which they had earlier initiated a cleaning inter- 

 action. When not thus engaged with black- 

 smiths, they swam in midwater showing no 

 apparent interest in the fishes around them but 

 occasionally picked at drifting scraps of debris, 

 usually algal fragments. During much of the 

 time that they swam in consort with blacksmiths, 

 they closely inspected these fish and actually 

 picked at their bodies a mean of 26 times (range 

 14-33). Of these picks, 27 9^ were made at the 

 base of the blacksmith's anal fin, 25% on the 



499 



