The histological characteristics of the digestive tract of four species of the Gobiidae, the hairychin goby (Sagamia geneionema), gluttonous goby (Chasmichthys gulosus), trident goby (Tridentiger obscurus), and guirine goby (Rhinogobius giurinus), collected from the coastal area of Jeju Island, Korea, were investigated. S. geneionema, which is a seawater species, has a short (RLG = 0.45), simple digestive tract, and lacks both a stomach and pyloric ceca. The mucosal folds are regularly branched and the muscularis extema is thickest in the esophagus. C. gulosus is also a seawater species. It has a short (RLG = 0.43), simple gut and stomach, but pyloric ceca are not observed. In the stomach, the lamina propria is well developed and contains many gastric glands. The mucosal folds have a complex branched form, and the muscularis externa is thickest in the esophagus. The digestive tract of T. obscurus, which is a brackish water species, is longer (RLG = 0.66) than that of the other species studied. This fish has a simple stomach but pyloric ceca are absent. The mucosal folds are regularly branched and the muscularis extema is thickest in the esophagus. R. giurinus, which is also a brackish water species, has a short (RLG = 0.42), simple, and narrow gut. The gastric glands are well developed in the stomach, but pyloric ceca are absent. The mucosal folds are regularly branched, and, as in the other species, the muscularis extema is thickest in the esophagus.
Materials and methods
2. Histological observations
3. Statistical analysis
1. Body length, digestive tract length, relative length of gut (RLG) and stomach contents
2. Histological characteristics