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Title: Development of red porgy Pagrus pagrus visual system in relation with changes in the digestive tract and larval feeding habits
Authors: Roo Filgueira, Francisco Javier 
Socorro, J.
Izquierdo López, María Soledad 
Caballero Cansino, María José 
Hernández Cruz, Carmen María 
Fernández Rodríguez, Antonio Jesús 
Fernández Palacios, Hipólito 
UNESCO Clasification: 251092 Acuicultura marina
Keywords: Red porgy
Visual system
Digestive tract
Issue Date: 1999
Publisher: 0044-8486
Journal: Aquaculture 
Conference: 8th International Symposium on Nutrition and Feeding of Fish
Abstract: Red porgy larvae, like other sparids such as red seabream are visual feeders. The normal development of the visual system is essential for successful prey capture and predator avoidance, leading to increased larval growth and survival. The aim of this work is to characterise the development of visual organs in relation to changes in the digestive system and feeding habits. Twenty-five larvae from hatching to day 29 were daily collected from the rearing tank, fixed in formalin, embedded in paraffin, 5 μm sectioned and stained with haematoxylin and eosin (H&E) and Periodic Acid Shift Reactive-Haematoxiline (PAS-Hx). Light microscopy was used to study changes in ocular morphology with respect to digestive system development. At hatching, eye and digestive systems of Pagrus pagrus larvae have no function. However, at day 3 post-hatch, when the mouth opens, the larvae must be ready for prey capture and digestion. Despite this, few day 3 larvae had food in the digestive tract. At day 4 photoreceptors were well developed in the eye, pigmentation pattern was complete and thus the visual system was completely ready for prey capture. This development coincided with detection of digestive activity in the midgut and most of larvae starting to take food. The results of this study suggest that adequate development of the visual system is important to establish the start of exogenous feeding. Besides, the appearance of rod cells increases larval photosensitivity and suggests that changes in lighting regimes could be necessary throughout the larval phase.
ISSN: 0044-8486
DOI: 10.1016/S0044-8486(99)00183-0
Source: Aquaculture [ISSN 0044-8486], v. 179 (1-4), p. 499-512
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