Sedberry and Cuellar: Planktonic and benthic feeding by Rhomboplites aurorubens 



705 



and he noted that the diet of juveniles (<100mm TL) 

 was dominated volumetrically by copepods. In the 

 present study, decapods dominated the diet volume of 

 fish less than 101mm SL. The feeding habits of ver- 

 milion snapper changed considerably with size in the 

 present study, although pelagic prey dominated in all 

 size classes. As vermilion snapper grows, it switches 

 from a diet of many small crustaceans, to a diet domi- 

 nated by a few large cephalopods, fishes, or decapod 

 crustaceans. The switch to different prey taxa and to 

 fewer, larger prey individuals was similar to ontogenetic 

 diet changes noted by Sedberry ( 1983 ) for several de- 

 mersal fishes from the outer continental shelf. In con- 

 trast, Schmitt and Holbrook (1984) found that black 

 surfperch iEmbiotoca jacksoni) switched to larger prey, 

 but that gross taxonomic composition of the diet did 

 not change and that surfperch continued to feed on 

 macrocrustaceans. in spite of growth and changes in 

 body size and foraging behavior. Vermilion snapper, 

 like many other fishes (Sedberry, 1983), apparently 

 becomes capable of taking larger prey as it grows and 

 switches from picking plankton to pursuing and cap- 



turing active nektonic species, such as Spanish sar- 

 dine (Sardinella aurita), and squids. 



Grimes (1979) suggested that vermilion snapper is 

 a nocturnal forager and that selective feeding by ver- 

 milion snapper on demersal zooplankton, such as 

 cumaceans, indicates nocturnal foraging. These crus- 

 taceans are infaunal in the sand or epifaunal in reef 

 crevices during the day but emerge at night (Anger 

 and Valentin, 1976; Alldredge and King, 1985), becom- 

 ing prey for vermilion snapper ancl other fishes that 

 forage on near-bottom zooplankton at night. Demersal 

 zooplankton demonstrating nocturnal emergence and 

 found in the diet of vermilion snapper included syllid 

 polychaetes, some calanoid copepods. cumaceans, am- 

 phipods, decapods, barnacle and stomatopod larvae, 

 chaetognaths and cephalochordates (Williams and 

 Bynum. 1972; Fincham. 1974; Anger and Valentin, 

 1976; Hobson and Chess, 1976; Alldredge and King, 

 1977; Hammer, 1981; Alldredge and King, 1985; Cahoon 

 and Tronzo, 1988). These taxa are dominant members 

 of the demersal zooplankton (Porter and Porter, 1977) 

 and emerge from benthic habitats at night when they 



