HOBSON: FEEDING RELATIONSHIPS OF FISHES 



Figure 32. — Paracirrhites forsteri, a hawkfish, seated on the reef during the day. 



much like that of P. arcatus, above, but it occurs 

 widely on different hard surfaces, rather than 

 being mostly associated, as is P. arcatus, with one 

 type of coral. In the manner typical of hawkfishes, 

 P. forsteri moves only infrequently, attacking 

 prey that have come within range of a short, ex- 

 plosive dash. Such attacks were seen only during 

 the day; at night P. forsteri generally is out of 

 sight in reef crevices. 



Thirty-six specimens (139: 93-181 mm) were 

 collected during day and night. Of the 28 that were 

 speared as they rested during midday on a variety 

 of reef substrata, 18 contained food in the stomach, 

 much of it relatively fresh (although in 1 the ma- 

 terial was reduced to unidentifiable fragments). In 

 contrast, among eight others that were speared 

 from deep within reef crevices during the 2 h im- 

 mediately before first morning light, four had 

 empty stomachs and three contained only well- 

 digested fi-agments; only the eighth specimen con- 

 tained relatively fresh prey — a shrimp, Saron 

 marmoratus — that appeared to have been taken 

 that night. 



Fish were the major prey, occurring in 14 of the 

 21 individuals that contained identifiable mate- 

 rial (mean percent of diet volume: 66.6; ranking 



index: 44.4). Other food items were: caridean 

 shrimps in four (mean percent of diet volume: 

 16.2; ranking index: 3.09), xanthid crabs in one 

 (mean percent of diet volume: 4.8; ranking index: 

 0.23), and unidentified crustacean fragments in 

 three (mean percent of diet volume: 12.4; ranking 

 index: 1.77). The only identifiable fish among the 

 gut contents was a wrasse, Thalassoma duperrey. 

 Three of the four individuals containing caridean 

 shrimps had preyed on Saron marmoratus. Of the 

 larger shrimps (to about 50 mm), this was the one 

 most frequently seen after dark, but only one of 

 these, noted above, appeared to have been cap- 

 tured at night. Perhaps significantly, the speci- 

 mens of P. forsteri that were examined had preyed 

 on either fishes or crustaceans, but never on both. 

 Hiatt and Strasburg (1960), citing the similar- 

 ity in habits between P. forsteri and P. arcatus, 

 noted that the diet of P. forsteri runs more to 

 fishes than crustaceans. I agree with them that 

 this difference probably relates to the size dif- 

 ference between these two congeners. 



CONCLUSION.^PamcjrrAi^es forsteri is a 

 diurnal predator that preys mostly on small fishes. 



987 



