HOBSON: FEEDING RELATIONSHIPS OF FISHES 



1967; Collette and Talbot, 1972). Hiatt and Stras- 

 burg ( 1960) attributed the high incidence of empty 

 stomachs in morays from the Marshall Islands 

 during daylight to nocturnal habits; however, I 

 concur with Gosline and Brock (1960), who attri- 

 buted the empty stomachs of Hawaiian morays 

 during the day to infrequent feeding, rather than 

 necessarily to nocturnal feeding. Certainly some 

 morays seem to be primarily nocturnal — Gymno- 

 thorax petelli and G. undulatus, described above, 

 are examples. But others described here, such as 

 G. meleagris, G. eurostus, and G. flavimarginata, 

 feed regularly in daylight. That some morays are 

 primarily diurnal was illustrated by Chave and 

 Randall (1971), who described a diurnally active, 

 nocturnally inactive pattern for G. pictus in the 

 central Pacific. Conclusions on relative activity 

 between day and night for moray eels remain 

 tenuous if based solely on how often, and at what 

 time, the species is seen in exposed positions. 

 Moray eels are adapted to activity within reef 

 crevices, and one would expect at least most of 

 them to best capture their prey there; indeed, most 

 species rarely expose themselves, day or night. 



Family Congridae: conger eels 



Conger marginaius Valenciennes — white eel, 

 puhi uha 



The white eel, which may exceed a length of 1 m 

 (Gosline and Brock, 1960), is relatively numerous 

 in Kona. It moves about in the open on the reef 

 after dark and rests in reef crevices during 

 daylight. In the Marshall Islands, Hiatt and 

 Strasburg (1960) reported similar behavior in C. 

 noordzieki, which preys on both fishes and 

 invertebrates. 



CONCLUSION. — Conger marginaius is active 

 in exposed locations on the reef after dark. 



Order Myctophiformes 

 Family Synodontidae: lizardfishes 



Sai<n'rfogracj7is(QuoyandGaimard)-"K/ae 

 nihoa 



Attaining lengths of over 300 mm, this is the 

 largest of those lizardfishes that are numerous on 

 the reef. During both day and night it rests mo- 

 tionless and fully exposed on sand patches, rock, or 

 coral. Despite these exposed positions, it is 



difficult to detect, so closely does its coloration 

 match the surroundings. Six specimens (223: 

 165-315 mm) were examined. The guts were 

 empty in five— four speared at night, between 

 2300 h and dawn, and one taken during midday. 

 The sixth specimen (165 mm), taken 1 h before 

 midnight, contained the well-digested anterior 

 halfofatrumpetfish, A i//ostomasc/zmens/s (about 

 90 mm when intact). Because digestion was far 

 advanced, this prey may have been ingested dur- 

 ing the previous day or evening twilight. These 

 limited data suggest that attacks are infrequent, 

 or perhaps that feeding habits are diurnal or cre- 

 puscular. Hiatt and Strasburg (1960) reported 

 strictly piscivorous habits for this species in the 

 Marshall Islands, and described daylight attacks 

 in which it darted upward from a resting spot on 

 the sea floor. 



CONCLUSION. — Saurida gracilis attacks 

 small fishes in daylight. 



Synodus variegatus (Lacepede) — ulae 'ula 



This is the most numerous synodontid on Kona 

 reefs. During both day and night it rests on the sea 

 floor (Figure 10), as does Saurida gracilis, above. 

 Although usually in exposed positions, it is 

 difficult to detect because its ' coloration closely 

 matches the background. Frequently it becomes 

 even more inconspicuous by burying in the sand, 

 leaving only its eyes and the tip of its snout ex- 

 posed. 



Once, during early afternoon, an individual of 

 this species shot up from the coral and captured a 

 small wrasse, Thalassoma lutescens, that I was 

 stalking. The wrasse was watching me when the 

 lizardfish struck, and the attacker may have 

 sensed this distraction in its prey. I speared the 

 predator immediately after the attack, and found 

 it to be 166 mm long (it lost the wrasse when 

 speared and is included below among those with 

 an empty gut). Two other noteworthy incidents 

 occurred at night: On both occasions I was hunting 

 specimens among the coral, and my spear, project- 

 ing into my path, was faintly illuminated by my 

 companion's diving light. Suddenly, an individual 

 of this species darted up and struck the silver barb 

 on the otherwise grey spear. Although the nearby 

 diving light created here an unnatural nocturnal 

 situation, these two fish obviously were alert for 

 prey at these times. 



Twelve specimens (142: 94-158 mm) were col- 

 lected during day and night from exposed posi- 



929 



