Date Awarded

1984

Document Type

Dissertation

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Virginia Institute of Marine Science

Abstract

The hypothesis is advanced that ophidiid fishes prevalent beneath oligotrophic tropical seas have evolved trophic specializations appropriate for existence in regions of low primary productivity where ultimate energy available for food production in benthic communities is low. The feeding strategies of these tropical dwelling deep-sea fishes are discussed within the context of this hypothesis. The feeding strategies of tropical dwelling deep-sea ophidiid fishes are examined through an analysis of food habits and examination of morphological features related to feeding. Three main modes of feeding are evident among these fishes: (1) predation upon small benthopelagic or planktonic organisms by small-bodied species of limited locomotory ability; (2) predation upon benthic-benthopelagic organisms with increasing reliance upon larger nektonic prey by mobile large-bodied species; (3) predation upon benthic organisms with diminished reliance upon benthopelagic and planktonic organisms. The first feeding mode is shown to be more widespread among deep-sea ophidiids studied. Ontogenetic feeding changes in select species show a shift from small benthic-benthopelagic prey in small fish to more mobile nektonic prey in larger fish. Smaller fish utilize such small-sized prey as calanoid copepods, gammarid amphipods and cumaceans, while larger fish show increasing reliance on decapods and fish. In contrast several small-bodied species studied showed no ontogenetic feeding changes in relation to prey size. Variation and select interrelations of morphological features related to feeding are studied in 18 species of ophidiids. Cluster analysis is employed as a verification procedure to determine the correspondence between feeding morphology and diet. Six morphological species groups are identified among species examined based on similarity of characters related to feeding. The results show poor correspondence between morphologically structured guilds based on characters assumed related to feeding and feeding guilds based on stomach content analysis. In addition morphological characters are interpreted ecologically based on information in the literature and gut content analysis. In several instances there is strong support of the hypothesized adaptations reported in the literature while in other cases there was little or no support. The functional relationship of the feeding apparatus is considered to better understand trophic specializations and feeding adaptations in these fishes. Dicrolene intronigra serves to illustrate the feeding mechanism in deep-sea ophidiid fishes. A basic description of the mechanical units of the head and their movements involved in feeding are presented.

DOI

https://dx.doi.org/doi:10.25773/v5-v7m8-1a83

Rights

© The Author

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