Ross L, Martinez-Palacios CA, Aguilar-Valdez MdC, Beveridge MCM & Chavez Sanchez MC (2006) Determination of feeding mode in fishes: The importance of using structural and functional feeding studies in conjunction with gut analysis in a selective zooplanktivore Chirostoma estor estor Jordan 1880. Journal of Fish Biology, 68 (6), pp. 1782-1794. https://doi.org/10.1111/j.1095-8649.2006.01061.x
Anatomical and histological studies of the endangered atherinid Chirostoma estor estor reveal that the species is ideally adapted to feeding on zooplankton. It has a superior protractile mouth with short unicuspid mandibular teeth. The buccal cavity is a highly adapted branchial sieve with branchial spines which develop in complexity with age to form a continuous flexible interdigitated mat. The filter bed has many of the characteristics of a cross-flow filter, which is ideal for a continuously feeding and filtering animal as the filter bed will not readily become occluded. The aggregates from the cross-flow filter pass to the rear of the buccal cavity where they are triturated by well-developed pharyngeal teeth. The species has a short intestine (<0·3 × body length) with no histological evidence of stomach-like structures, no pyloric caecae and with trypsin-like enzymes operating at high pH. Feeding trials with natural plankton showed a sequence of particle size selection as the animals grow, with older animals taking cladocerans up to 700 μm in diameter. Although some adults occasionally take small fish prey, cumulatively, the present studies indicate that the fish is a zooplankton feeder throughout all its life stages.
Journal of Fish Biology: Volume 68, Issue 6