Organization of the Digestive Tract and Localization of Protein Fibre in Electrophorus sp. (Gymnotiformes: Gymnotidae)

ABSTRACT

Research into the electric eel ( Electrophorus ) has focused on its production of high‐voltage electrical discharges for predation and defence, and its divergence from other fish species in terms of molecular activities. However, the knowledge of its digestive biology remains limited. Here, using conventional histological and histochemical methods, we elucidate the structure of the digestive tract, including accessory digestive organs, and the localization of protein fibres in Electrophorus sp. Our observations of the morphological organization of the digestive tract in the coelomic cavity revealed that all regions presented a typical four‐layer organization (mucosa, submucosa, muscularis, and serosa). Both the stomach and intestine had well‐developed histological layers. The anterior intestine exhibited well‐developed longitudinal folds while the posterior intestine exhibited a slight longitudinal fold. Specialized mucus‐secreting cells were widely distributed throughout the digestive epithelial tract, particularly the submucosa in the stomach. Histochemical analyses demonstrated a wide distribution of collagen and elastic fibres throughout the digestive tract, with prominence in the muscularis layer. These findings provide updated foundational anatomical information on the digestive system of the electric eel, supporting future studies on its digestive physiology and feeding evolution.