FEEDING RELATIONSHIPS OF TELEOSTEAN FISHES 

 ON CORAL REEFS IN KONA, HAWAII 



Edmund S. Hobson^ 



ABSTRACT 



Feeding relationships of teleostean fishes on coral reefs at Kona, Hawaii, were studied during 1969 and 

 1970. 



Fishes that have a generalized feeding mechanism, including those carnivores whose morphologies 

 place them close to the main line of teleostean evolution, are predominantly nocturnal or crepuscular. 

 These include holocentrids, scorpaenids, serranids, apogonids, priacanthids, and lutjanids. The major 

 prey of the nocturnal species are small, motile crustaceans, which are most available to the direct 

 attacks of generalized predators when they leave their shelters after dark. The major prey of the 

 crepuscular species are smaller fishes, whose defenses against direct attacks of generalized predators 

 are less effective during twilight. Feeding by generalized predators during the day depends largely on 

 being within striking distance of prey that make a defensive mistake, a position best attained by those 

 predators that ambush their prey from a concealed position, or by those that stalk. 



Ambushing and stalking tactics have produced some highly specialized forms that, during the day, 

 prey mostly on smaller fishes. Diurnal ambushers include the highly cryptic synodontids, scorpaenids, 

 and bothids; diurnal stalkers include aulostomids, fistulariids, belonids, and sphyraenids — all of them 

 long, attenuated fishes. 



Some predators — most notably the muraenid eels — are specialized to hunt deep in reef crevices, and 

 here they capture some of the many small animals that shelter themselves in those crevices, day and 

 night, when resting, injured, or distressed. Mullids use their sensory barbels to detect small animals 

 that have sheltered themselves amid the superficial covering on the reef, or in the surrounding sand; at 

 least some mullids further use their barbels to drive these prey into the open. 



Most of the fishes on Kona reefs are among the more highly evolved teleosts, having reached, or 

 passed, the percoid level of structural development. The adaptability of the feeding apparatus in these 

 more advanced groups has given rise to a wide variety of specialized species, including both carnivores 

 and herbivores, that have diverged from one another mostly on the basis of differing food habits. These 

 fishes, most of which are diurnal, include the chaetodontids, pomacentrids, labrids, scarids, blenniids, 

 acanthurids, and Zanclus, among the perciforms; and the balistids, monacanthids, ostraciontids, 

 tetraodontids, canthigasterids, and the nocturnal diodontids, among the tetraodontiforms. With their 

 specialized feeding structures and techniques, these fishes consume organisms like sponges, coelenter- 

 ates, large mollusks, tunicates, and tiny or cryptic Crustacea that are protected by behavioral or 

 anatomical features from fishes not appropriately specialized. 



Many important ecological relations among 

 marine fishes are understood only by considering 

 in broad overview during both day and night the 

 different forms living together under natural con- 

 ditions. With this in mind, I undertook a broad 

 study of reef fishes at Kona, Hawaii, between June 

 1969 and August 1970. A segment of this study 

 dealing with the twilight situation was published 

 earlier (Hobson, 1972). The present report de- 

 scribes the situations that prevail throughout day 

 and night. The work is centered on direct observa- 

 tions of activity in the fishes, as was my earlier 

 study of predatory behavior of shore fishes in the 

 Gulf of California (Hobson, 1968a), but here with 



'Southwest Fisheries Center Tiburon Laboratory, National 

 Marine Fisheries Service, NOAA, P.O. Box 98, Tiburon, CA 

 94920. 



greater emphasis on detailed analysis of food 

 habits. 



Several other workers adopted broad overviews 

 in considering fishes of various areas. Limbaugh 

 (1955) studied fishes in California kelp beds dur- 

 ing the day, whereas Starck and Davis (1966) 

 described the habits of fishes in the Florida Keys 

 at night; both of these studies present extensive 

 direct observations of activity, but little data on 

 food habits. On the other hand, Hiatt and Stras- 

 burg ( 1960), as well as Randall ( 1967 ), and Quast 

 (1968 ), treated extensively the food habits of fishes 

 collected during daylight in the Marshall Islands, 

 the West Indies, and southern California, respec- 

 tively, but offered relatively few direct observa- 

 tions of activity. Suyehiro (1942) comprehensively 

 treated the feeding morphology of fishes in Japan 



Manuscript accepted February 1974. 

 FISHERY BULLETIN; VOL. 72, NO. 4, 1974. 



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