Abstract
Previous studies of the relationships between feeding habits and mouthpart structures have suggested that copepods of the family Pontellidae are carnivores. A re-evaluation of this hypothesis by scanning electron microscope (SEM) study of Pontella meadii, Labidocera aestiva, Anomalocera ornata (family Pontellidae) and Acartia tonsa (family Acartiidae) revealed that the mandibular blades of all four species are capable of macerating diatoms and the 2nd maxillae are capable of retaining nanoplankton. SEM studies of the contents of natural-diet fecal pellets showed that all four copepods ate a variety of diatoms in nature. Animal remains were observed in the feces of P. meadii and L. aestiva. All four copepods ate the diatom Thalassiosira fluviatilis in unialgal cultures, and ingestion rates were directly related to fecal pellet production rates for all copepods except A. tonsa. Assimilation of a unialgal diet of T. fluviatilis by P. meadii was high (75.6-97.8%) at lower food levels, but a decline in assimilation (31.2-50.3%) at higher food levels suggested that superfluous feeding occurred. Thus, there is a mechanical basis, as well as direct evidence for classifying these copepods as omnivores, even though three of them belong to a family previously classified as carnivorous.
Turner, Jefferson Taylor (1977). Trophodynamic studies of four Gulf of Mexico copepods and their fecal pellets. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -358526.