chapter  8
22 Pages

Food Consumption and Feeding Habits

ByBradley M. Wetherbee, Enric Cortés

CONTENTS 8.1 Introduction .................................................................................................................................. 225 8.2 Diet ............................................................................................................................................... 226

8.2.1 Quantification of Diet ..................................................................................................... 226 8.2.2 Broad Dietary Groups..................................................................................................... 227 8.2.3 Diet Shifts........................................................................................................................ 228 8.2.4 Feeding Relationships ..................................................................................................... 229 8.2.5 Feeding Patterns .............................................................................................................. 230 8.2.6 Trophic Levels................................................................................................................. 231

8.3 Food Consumption ....................................................................................................................... 231 8.3.1 Daily Ration .................................................................................................................... 231 8.3.2 Gastric Evacuation .......................................................................................................... 232

8.4 Excretion and Egestion ................................................................................................................ 235 8.4.1 Excretion ......................................................................................................................... 235 8.4.2 Egestion ........................................................................................................................... 235

8.5 Production..................................................................................................................................... 236 8.6 Conclusions .................................................................................................................................. 237 References .............................................................................................................................................. 237

8.1 Introduction Although it is widely recognized that sharks and other elasmobranchs often play a role in the transfer of energy between upper trophic levels within marine ecosystems, our understanding of the dynamics of prey consumption and processing of food in elasmobranchs remains rudimentary. To fully comprehend energy flow through elasmobranchs in marine communities it is necessary not only to know what they eat, but also to characterize the rates at which they ingest, digest, and process energy and nutrients contained in prey that is consumed. As with other areas of elasmobranch biology, investigations on dynamics of feeding and processing food lag behind such studies on other marine fishes and vertebrates. By far the most common elasmobranch feeding studies simply describe stomach contents of a particular species in a particular location. Rate of consumption, feeding patterns, and the fate of food once ingested have been examined for very few species of elasmobranchs.