HOBSON: FEEDING RELATIONSHIPS OF FISHES 



Figure 41. — Arothron meleagris, a balloonfish. By inflating its saclike body with water, this slow-swimming fish 

 increases its size, which presumably decreases its vulnerability to predators. 



Pontes, whereas six had taken tunicates (mean 

 percent of diet volume: 44.4; ranking index: 33.3), 

 all of them a large colonial form with a heavy, 

 black integument that, like the coral, encrusts on 

 rocks. The only other recognizable items were pec- 

 tinid pelecypods in one (mean percent of diet vol- 

 ume: 0.6; ranking index: 0.08). Three contained 

 unidentifiable fragments (mean percent of diet 

 volume: 11.9; ranking index: 4.46). Thus, these 

 data indicate that, compared with A. hispidus, A. 

 meleagris is a relatively specialized feeder. The 

 three A. meleagris that Hiatt and Strasburg 

 (1960) examined in the Marshall Islands had fed 

 almost exclusively on living corals. 



CONCLUSION. — Arothron meleagris is a diur- 

 nal predator that feeds mostly on corals and tuni- 

 cates which encrust on rocks. 



General Remarks on Balloonfishes 



fishes crush an array of armored organisms that 

 are unavailable as prey to most other fishes (Hiatt 

 and Strasburg, 1960). 



Family Canthigasteridae: sharpbacked 



puffers 



Canthigaster amhoinensis Bleaker — 

 pu'j/ ola'i 



This pufferfish occurs chiefly in relatively shal- 

 low water where there is much exposed basalt. It is 

 a solitary fish, active close to the sea floor during 

 the day, but only infrequently in view after dark, 

 when, presumably, it generally retires to reef 

 crevices. 



All 11 individuals (69: 31-91 mm) that were 

 speared at various times during daylight con- 

 tained identifiable material (much of it fresh), as 

 listed in Table 71. 



The dentition of tetraodontids consists of heavy 

 plates, two in each jaw, that form a sharp beak. 

 With this exceptionally strong apparatus, these 



CONCLUSION. — Canthigaster amboinensis 

 is a diurnal omnivore that feeds mostly on coral- 

 line algae and various hard-bodied invertebrates. 



1013 



