FISHERY BULLETIN: VOL. 72, NO. 4 



Predators having obvious morphological and 

 behavioral specializations that increase their 

 proficiency as ambushers or as stalkers are consid- 

 ered in the next section. 



Specialized Offshoots from the Main 

 Line of Teleostean Evolution 



Most fishes inhabiting tropical reefs today, as 

 exemplified by species in Kona, represent 

 specialized offshoots from the main teleostean 

 line. 



Predators Specialized to Ambush Prey 



As emphasized in the introductory remarks, the 

 categories erected in this discussion overlap. This 

 is especially true of predators that ambush their 

 prey. By using this tactic, predators with the 

 generalized feeding mechanism increase their 

 capacity to capture prey in daylight. But many 

 ambushers, like certain species of Epinephelus, 

 are so similar in both morphology and habits to 

 many of the nocturnal and crepuscular forms dis- 

 cussed above that one can only arbitrarily distin- 

 guish them as being specialized in this activity. 

 Nevertheless, some forms have retained the 

 generalized feeding mechanism while diverging 

 widely from the primitive form in other respects. 

 And the divergence is based on features that bet- 

 ter adapt these fishes for the ambushing tactic. 



The synodontids, order My ctophi formes, which 

 are prominent ambushers in Kona, as they are on 

 most other tropical reefs, are products of an 

 evolutionary offshoot that diverged from the main 

 line at a preacanthopterygian level. Thus, the 

 ambushing tactic has had a long history. The scor- 

 paenids, order Scorpaeniformes, and the bothids, 

 order Pleuronectiformes, both of whose Kona rep- 

 resentatives include specialized ambushers, be- 

 long to groups that diverged from the mainstream 

 near the percoid level (Gosline, 1971; and others). 

 Significantly, the adults of all these forms seem to 

 be primarily piscivorous during the day. 



The synodontids, scorpaenids, and bothids that 

 ambush their prey have acquired characteristics 

 that camouflage them as they lie on the sea floor. 

 Clearly, it is important for these predators to go 

 unseen by their victims. In this respect, many of 

 the cirrhitids, order Perciformes, might seem a 



puzzle. An example from Kona is Paracirrhites 

 forsteri (Figure 32), which preys mostly on smaller 

 fishes during the day. Although attacking prey in 

 much the same manner as other ambushers, this 

 colorful fish is clearly visible as it rests in exposed 

 positions on the reef. Selection, in this case, may 

 have in fact favored coloration that attracts atten- 

 tion. Conceivably this could be an effective offen- 

 sive characteristic, just so long as its use among 

 predators is limited. It is well known that certain 

 small fishes are attracted to conspicuous objects on 

 the sea floor — one needs only to place a small, 

 shiny artifact on the bottom to see this. Perhaps P. 

 fosteri actually finds prey among small fishes that 

 approach to investigate its conspicuous features. 



Predators Specialized to Stalk Prey 



Many predators specialized to stalk prey in the 

 water column belong to groups whose ancestors 

 diverged from the main teleostean line below the 

 percoid level. Characteristically, they have long, 

 attenuated bodies. Among species whose behavior 

 in Kona is described above are the trumpetfish, 

 Aulostomus chinensis, and the cornetfish, 

 Fistularia petimba — both of the order Gasteros- 

 tei formes. 



Two other highly specialized stalkers on Kona 

 reefs were not included in the species accounts 

 above because observations on them were infre- 

 quent; these are the needlefish, Strongylura 

 gigantea, order Atheriniformes, and the bar- 

 racuda, Sphyraena barracuda, order Perciformes. 

 The various species of needlefishes and bar- 

 racudas are widespread on tropical reefs, and their 

 stalking habits are well documented. Hiatt and 

 Strasburg (1960) reported that Strongylura 

 gigantea feeds on small fishes in the Marshall 

 Islands by "drifting up to them and suddenly lash- 

 ing out with its jaws." On the basis of similar 

 observations in the tropical Atlantic, Randall 

 (1967) reported that needlefishes are almost ex- 

 clusively piscivorous, and that they "drift slowly 

 into range of one of their prey before making a 

 quick rush." Regarding barracudas, Hiatt and 

 Strasburg (1960) told of Sphyraena genie in the 

 Marshall Islands "drifting solitary near the sur- 

 face stalking its prey" and stated that "it surprises 

 its victim with a sudden lunge." Randall (1967) 

 noted that barracudas in the tropical Atlantic feed 

 primarily on fishes during the day, a statement 

 probably true of at least most stalking predators. 



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