Food and feeding mechanisms of Gilchristella aestuarius (Pisces: Clupeidae)

Abstract

From December 1980 to June 1981 a total of 180 specimens of the estuarine round-herring Gilchristella aestuarius were collected for stomach content analysis. Diatoms were the most frequently ingested food item, although the gill raker gap was too large to retain these and other planktonic food items. Mucus-secreting cells within the epithelial layer of the hyoid arch, branchial arches and gill rakers, trap the plankton which accumulate in boluses of mucus-enveloped food too large to pass through the gill rakers. G. aestuarius was found to possess a pair of suprabranchial pouches. The histology of the walls of these organs and the external attachment of six muscle blocks indicates a feeding mechanism involving the accumulation and temporary storage of diatoms and other planktonic food items, which are then coalesced into a pellet large enough to be swallowed by peristalsis into the stomach.