Trophic ecomorphology of cardinalfish

Abstract

Trophic diversity in 9 cardinalfish species was investigated by comparing 14 morphological characteristics of their feeding apparatus with dietary data based on stomach content analysis. Analysis of the morphological characteristics separated the 9 species into 3 distinct groups. The first group (Cheilodipterus macrodon, C. artus and C. quinquelineatus) was characterized by elongated heads; the second group (Archamia fucata, Apogon guamensis, A. cyanosoma and A. fragilis) by large gapes; and the third group (Apogon exostigma, A. doederleini) by wider heads and low transmission coefficient in their jaw mechanics. Stomach samples, however, revealed that morphology was of limited utility in predicting dietary groupings. The majority of species examined displayed generalist diets. The results indicate that while morphology may predict feeding potential, or feeding mode, actual resource use in this group may be shaped primarily by other modifying factors such as behaviour and prey availability. In contrast to other reef fish groups, morphology does not appear to play a strong role in influencing diet in the Apogonidae.