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Trichomycterus bogotensis is one of the three species of fish that inhabit the Colombian Andes. However, several aspects of its basic biology, including its digestive system, are unknown. The morphology and histology of the digestive system are of great importance for understanding a species' feeding habits and food preferences. Thus, this study aimed to perform a morphological description of the digestive tract of T. bogotensis. The gastrointestinal tract of seven specimens was processed for paraffin histology, high-resolution optical microscopy, and transmission electron microscopy. Anatomically, T. bogotensis exhibits a terminal mouth with villiform teeth, a narrow esophagus, a large and muscular stomach, and a short intestine. Histology and ultrastructure revealed a tissue organization similar to that reported for other Silurids, composed of four layers: mucosal, submucosal, muscular, and serosa. The anatomical and histological characteristics suggest that T. bogotensis is a benthic species with a tendency to carnivory. [ABSTRACT FROM AUTHOR]

The cardinal tetra Paracheirodon axelrodi is a species of the family Characidae of great interest as an ornamental fish. Many aspects of the biology of this species are still unknown. The present work presents a complete description of the different components of the digestive tract of P axelrodi, analyzing its global anatomical arrangement, the adjacent glands (liver and pancreas) and the previously ignored pyloric caeca, using histological and histochemical techniques with light microscopy and scanning electron microscopy. Three levels of analysis were performed: macroscopic anatomy, histology of the gastrointestinal tract and scanning electron microscopy of mucosal surfaces. The intestinal coefficient (Ci) of P. axelrodi calculated here (0.94) is within the expected range for a carnivorous species. The anatomy of the alimentary and the resulting Ci is consistent with carnivorous diet in line with dietary studies in the wild in this species. The digestive tract, including adjacent glands (liver and pancreas), presented a relatively conserved general pattern within that described for other species of the family Characidae, especially at the histological level. [ABSTRACT FROM AUTHOR]

Abstract The cardinal tetra Paracheirodon axelrodi is a species of the family Characidae of great interest as an ornamental fish. Many aspects of the biology of this species are still unknown. The present work presents a complete description of the different components of the digestive tract of P. axelrodi, analyzing its global anatomical arrangement, the adjacent glands (liver and pancreas) and the previously ignored pyloric caeca, using histological and histochemical techniques with light microscopy and scanning electron microscopy. Three levels of analysis were performed: macroscopic anatomy, histology of the gastrointestinal tract and scanning electron microscopy of mucosal surfaces. The intestinal coefficient (Ci) of P. axelrodi calculated here (0.94) is within the expected range for a carnivorous species. The anatomy of the alimentary and the resulting Ci is consistent with carnivorous diet in line with dietary studies in the wild in this species. The digestive tract, including adjacent glands (liver and pancreas), presented a relatively conserved general pattern within that described for other species of the family Characidae, especially at the histological level.

In view of the great diversity of dietary habits among bats, and the need for morphological adaptations in their digestive system, this study characterized and compared the morphology of the small (SI) and large intestines (LI) of the bats Artibeus planirostris (Phyllostomidae: Stenodermatinae) and Diphylla ecaudata (Phyllostomidae: Desmodontinae), and interpret their morphologies in the context of dietary differences. We hypothesized that diet could influence the morphological characteristics in these two species by means of a more complex intestinal morphology in A. planirostris than in D. ecaudata. The intestines were histologically processed, stained, and analyzed. Despite body mass differences, total intestinal length were almost two folds higher in A. planirostris than in D. ecaudata, and the intestinal coefficient, which quantifies the investment in intestines in relation to the body mass, wasn't statistically different. Macroscopically, no distinction was observed between the SI and LI, and few differences allowed to distinguish histologically the regions of the SI in both species. We found a typical organization of Peyer's patches only in D. ecaudata. Enteroendocrine cells were more frequently observed at caudal parts of the small intestine in both species. In A. planirostris, the SI diameter, the thickness of its wall, and the thickness and percentage occupied by the mucosal layer, as well as the wall thickness of its LI, were greater than those in D. ecaudata. Circular folds were observed only in the LI of A. planirostris. We speculate that these differences represent strategies to increase the contact surface available to optimize nutrient uptake in A. planirostris; while the hematophagous feeding habit of D. ecaudata, predominantly proteinaceous and semifluid, has a gut wall characterized with less morphological complexity and specializations; which confirms our hypothesis. Based on the similarities and differences founded, it can be concluded for both species that the reduction in the anatomical structures, associated with the microscopic findings, allows to optimize the absorption of nutrients and water in these bats when compared to other mammals; a similar pattern to that found in other chiropterans. [ABSTRACT FROM AUTHOR]

The diet of the catfish, Clarias buthupogon, was studied in two forest rivers in the Yoko Reserve, the Yoko and Biaro Rivers, from September 2008 to August 2009. Gill nets, long lines and traditional traps were used to catch the fish. An analysis of the contents of 409 stomachs yielded 22 prey Families, 11 Orders and 4 Classes, grouped into 15 major food categories. Indices of weight and volumetric occurrences indicated that Clarias buthupogon eats aquatic insects, crustaceans, oligochaetes, molluscs, animal and plant debris. The average intestinal coefficient was 0.84, which places the species among the insectivorous-prone omnivores. The diet according to sex, season, length and height, and location inside and outside the Yoko Reserve revealed that similar prey items were consumed in similar proportions. The calculated Schöner Index indicates an overlap of diet between seasons and sex. [ABSTRACT FROM AUTHOR]

The anatomical arrangement of the digestive tract and the length (cm) of the oesophagus and intestine of the catfish Lophiosilurus alexandri were described, and the intestinal coefficient was determined. L. alexandri oesophagus is short, in median position, and presents longitudinally folded mucosa, whilst its epithelium is stratified and non‐keratinised, with mucous, claviform and epithelial cells. Stomach has "C" shape, with folded mucosa along cardiac region, disordered in the fundic region, and directed to the sphincter in the pyloric region. Its epithelium is simple prismatic, and cardiac and fundic portions have gastric glands. Cranial intestine is formed by pyloric flexure and descending loop attached to the right side of stomach. Middle intestine is winding and positioned to the right of caudal portion of stomach. Caudal intestine is linear and with a median position up to the anus. Intestinal coefficient was 1.39 ± 0.30 cm. Epithelium is simple prismatic with brush border and contains epithelial and goblet cells. Caudal region has highest concentration of goblet cells. Were detected neutral glycoproteins, carboxylated and sulphated acid glycoconjugates for mucous cells and goblet cells, and neutral glycoproteins for the apical region of gastric epithelial cells. Morphological features could be related to piscivorous species feeding habit. [ABSTRACT FROM AUTHOR]

ABSTRACT The present study aimed to investigate the macroscopic and histological structure of the gastrointestinal tract (GIT) of Larimichthys crocea (Richardson, 1846). It consists of esophagus, stomach regions, pyloric caeca, intestinal regions, and rectum. Sixteen tubular light yellowish pyloric caeca of similar sizes were observed in all individuals. The digestive wall consists of mucosa, submucosa, muscularis, and adventitia. No major differences appeared in the structure of the tunica, epithelial cell types, connective tissues and musculature glands of L. crocea GIT. The mucosal epithelia in the oesophagus has longitudinal branched folds with frontward and hindmost zones. The gastric tunica mucosa has a characteristic folded structure and can be divided into three regions. The intestinal tunica mucosa is characterized by villi structures and numerous mucus-secreting cells. Mucus-secreting goblet cells were strongly positive to AB at pH 2.5 in the oesophagus (excluding gastro-oesophageal junction) and intestine mucosal regions, which indicates an abundance of carboxylate mucins. The surface epithelia of the gastric mucosa is PAS-positive and AB-negative. SEM examination revealed that cells in the epithelium of the esophagus have an unbroken apical layer and goblet cells. The intestinal coefficient (IC) of L. crocea was 0.80 ± 0.21, consistent with a carnivorous or omnivorous habit. Our study adds the knowledge of the digestive system of L. crocea and might be useful in the management of L. crocea stocks.

The present study aimed to investigate the macroscopic and histological structure of the gastrointestinal tract (GIT) of Larimichthys crocea (Richardson, 1846). It consists of esophagus, stomach regions, pyloric caeca, intestinal regions, and rectum. Sixteen tubular light yellowish pyloric caeca of similar sizes were observed in all individuals. The digestive wall consists of mucosa, submucosa, muscularis, and adventitia. No major differences appeared in the structure of the tunica, epithelial cell types, connective tissues and musculature glands of L. crocea GIT. The mucosal epithelia in the oesophagus has longitudinal branched folds with frontward and hindmost zones. The gastric tunica mucosa has a characteristic folded structure and can be divided into three regions. The intestinal tunica mucosa is characterized by villi structures and numerous mucus-secreting cells. Mucus-secreting goblet cells were strongly positive to AB at pH 2.5 in the oesophagus (excluding gastro-oesophageal junction) and intestine mucosal regions, which indicates an abundance of carboxylate mucins. The surface epithelia of the gastric mucosa is PAS-positive and AB-negative. SEM examination revealed that cells in the epithelium of the esophagus have an unbroken apical layer and goblet cells. The intestinal coefficient (IC) of L. crocea was 0.80 ± 0.21, consistent with a carnivorous or omnivorous habit. Our study adds the knowledge of the digestive system of L. crocea and might be useful in the management of L. crocea stocks. [ABSTRACT FROM AUTHOR]

The relationship between ontogenetic variation of intestine length and feeding habits of five stream-dwelling fish species from the Ubatiba River were investigated. Analysed data were based on two size categories (juveniles and adults) and two food categories (animal and vegetal). Diet composition of each size category revealed that Astyanax janeiroensis and Geophagus brasiliensis changed food preference throughout ontogeny and switched from omnivorous/carnivorous to omnivorous/herbivorous and from omnivorous/carnivorous to omnivorous, respectively. These changes were followed by ontogenetic changes in the Intestinal Coefficient (IC). No ontogenetic differences were registered for IC and food categories consumed by Hoplias malabaricus but significant differences in the size of consumed preys as well as positive correlation between fish size (predator) and prey size was observed. Food items (within animal category) consumed by the adult Pimelodella lateristriga were mainly based on allochthonous arthropods whereas juvenile individuals fed with the same intensity on allochthonous and autochthonous arthropods; both juveniles and adult individuals of Mimagoniates microlepis were mainly allochthonous feeders. Mean IC values of Pimelodella lateristriga and Mimagoniates microlepis did not change along body growth. Although changes in food category consumption were not common among all the studied species, changes in the resource exploitation strategy was a rule among them, except for Mimagoniates microlepis.Foi investigada a relação entre as variações ontogenéticas do comprimento do intestino e os hábitos alimentares de cinco espécies de peixes do rio Ubatiba, RJ. Os dados analisados foram baseados em duas categorias de tamanho (jovens e adultos) de cada espécie e duas categorias de alimento (animal e vegetal). A composição da dieta de cada categoria de tamanho revelou que Astyanax janeiroensis e Geophagus brasiliensis mudaram a preferência alimentar ao longo do desenvolvimento ontogenético e alternaram entre onívoros / carnívoros para onívoros / herbívoros e entre onívoros / carnívoros para onívoros, respectivamente; essas alterações foram acompanhadas por alterações ontogenéticas do Coeficiente Intestinal (CI). Não foram registradas diferenças relacionadas à ontogenia tanto para o CI como para as categorias de alimento consumidas por Hoplias malabaricus mas, dentro da categoria animal, foram observadas diferenças significativas para o tamanho das presas consumidas, bem como correlação positiva entre o tamanho do peixe (predador) e o tamanho da presa. Foi ainda observado que os itens alimentares (dentro da categoria animal) consumidos pelos adultos de Pimelodella lateristriga foram principalmente baseados em artrópodes alóctones, enquanto os jovens consumiram na mesma intensidade artrópodes alóctones e autóctones; tanto os jovens como os adultos de Mimagoniates microlepis se alimentaram principalmente de artrópodes alóctones. Os valores médios do CI de P. lateristriga e M. microlepis não variaram ao longo do crescimento do corpo. Apesar do consumo das diferentes categorias tróficas não ter sido registrado para todas as espécies estudadas, as alterações da estratégia de exploração dos recursos foi a regra entre essas espécies, exceto para M. microlepis. Dessa forma, sugerimos que M. microlepis é uma espécie conservadora, no que se refere a estratégia de forrageamento e que as alterações nas estratégias tróficas das outras quatro espécies podem ser explicadas pelas alterações morfológicas e maturacionais, particularmente pela habilidade na capacidade exploratória e/ou locomotora.