HOBSON: FEEDING RELATIONSHIPS OF FISHES 



Table 30. — Food of Hemitaurichthys zoster. 



Of eight specimens (118: 110-125 mm) col- 

 lected, one that was taken during early morning 

 twilight close among cover contained only a few 

 well-digested fragments, whereas all seven that 

 were active above the reef when taken during the 

 afternoon were full of food (much of it fresh), as 

 listed in Table 32. 



CONCLUSION. — Chaetodon miliaris is a diur- 

 nal planktivore that takes mostly copepods. 



Chaetodon quadrimaculatus Gray — 

 four-spot butterflyfish 



This butterflyfish is especially numerous where 

 the water is less than 10 m deep over reefs rich in 

 the coral Pocillopora. During the day it is active, 

 solitary or paired, close to the sea floor. Feeding 

 strictly on the bottom, it mostly picks at the sur- 

 face of living coral or in cracks within dead coral 

 and basalt. It occurs in the same areas at night, 

 but though alert, seems relatively inactive. 



Twenty-six specimens (92: 43-110 mm) were 

 speared during day and night. All 15 collected 

 during midday were full of food, as were 4 of 5 

 taken at night during the 2 h immediately before 

 midnight (the fifth was empty). The remaining six 

 were collected at night during the hour im- 

 mediately before daybreak, and while three of 

 these had empty stomachs, the other three were 

 full. Whether these findings indicate nocturnal 

 feeding or slow digestion remains uncertain. No 

 differences were recognized in composition or con- 

 dition of gut contents between specimens taken 

 day and night. Items in the 22 individuals contain- 

 ing identifiable material are listed in Table 33. 



At least some of the corals taken by this fish 

 probably are soft corals. Most material in the gut 

 appeared as amorphous clumps rich in nemato- 

 cysts and zooxanthellae. That much of this is soft 

 coral seems likely considering how often C. quad- 

 rimaculatus nibbles about reef crevices where liv- 

 ing stony corals are absent. 



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