HOBSON: FEEDING RELATIONSHIPS OF FISHES 



Figure 8. — Gymnothorax meleagris, a moray eel, showing daytime attitude. 



Gymnothorax eurostus (Abbott) 



This small species, which attains a maximum 

 length of about 60 cm, is probably the most 

 numerous moray in Hawaii (Gosline and Brock, 

 1960). However, it is a secretive species, only occa- 

 sionally visible on the reef. Although the four in- . 

 dividuals collected (360: 294-432 mm) were 

 speared as they protruded their heads from holes 

 in the reef during the day, this habit is not charac- 

 teristic of G. eurostus, as it is of G. meleagris, 

 above. Two of those collected had empty stomachs, 

 but the other two, both taken during midday, con- 

 tained relatively fresh prey — a caridean shrimp in 

 one, a xanthid crab in the other. 



CONCLUSION.— G.vm/^oMorax eurostus 

 captures crustaceans during the day. The night- 

 time situation remains uncertain. 



Gymnothorax flavimarginata (Riippell) — puhi 

 paka 



This eel, which attains a length of about 120 cm 

 (Gosline and Brock, 1960), is the most numerous of 

 the larger muraenids in Kona. Being so abundant. 



as well as large, this heavy-bodied eel probably 

 represents the greatest threat among morays to 

 humans. It is the species that most often appears 

 when a fish has been speared during daylight. The 

 regularity and promptness of these appearances 

 make it clear that G. flavimarginata is especially 

 sensitive to fish that are injured, or perhaps 

 otherwise under stress. In this respect it is similar 

 to G. castaneus in the Gulf of California (Hobson, 

 1968a). Usually when a reef fish is injured, or 

 seriously threatened, it takes cover in a reef crev- 

 ice. Usually such individuals are to some extent 

 incapacitated, and thus vulnerable to preda- 

 tors equipped to seek them out. Probably G. 

 flavimarginata is adapted to this task. Other large 

 morays on the reef show the same behavior, but to 

 a lesser degree. Most encounters with G. 

 flavimarginata were by day; although its behavior 

 would seem equally adaptive to nocturnal condi- 

 tions, it was only occasionally observed after dark. 



CONCLUSION. — Gymnothorax flavimarginata 

 is especially sensitive to stimuli emanating from 

 a fish in distress, and appears adapted to seeking 

 out such individuals when they have sought 

 shelter in reef crevices. 



927 



