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
Abstract: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 m 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.
Document Type: Regular Paper
Affiliations: 1: Coordinación de la Investigación Científica, Ciudad Universitaria, Universidad Michoacana de San Nicolás de Hidalgo, Michoacán, Morelia, México 2: Fisheries Research Services, Freshwater Laboratory, Faskally, Pitlochry, PH16 5LB, Scotland, U.K. 3: Unidad Mazatlán en Acuicultura y Manejo Ambiental del CIAD, A.C. Av. Sábalo Cerritos s/n, Apdo Postal 711. Mazatlán, CP. 82010, Sinaloa, México
Publication date: June 1, 2006