This study compares the morphology and cytology of the alimentary tract in several species of lizardfishes (Synodontidae, Teleostei) of the genera Saurida, Synodus, and Trachinocephalus, in relation to their diets and bathymetric distribution. All the studied species feature a large, pouch-like stomach, with the intestine beginning at the stomach's anterior apex, adjacent to the esophageal opening. In the more 'microphagous'Synodus spp. and Trachinocephalus, the intestine bends twice before reaching the anus, whereas in the more 'macrophagous'Saurida spp., the intestine extends straight to the anus. The species differ also in the number and form of their pyloric ceca, the length of the intestine and in the percentile relationship between stomach length and standard body length. Along the alimentary tract folds and villi protrude into the lumen, their numbers differing on various sites of the tract. Three cell types make up the gastric gland system: (1) pyramidal cells forming the tubular gastric glands in the lamina propria; among them are large, pale secretary cells; (2) groups of neck cells that surround the pits of the tubules; and (3) groups of large and granule-rich cells at the end portion of the stomach. All species are carnivorous and uniform in morphology, the differences in the alimentary tract found between the more shallow-water species of Synodus and Trachinocephalus, and the deeper-dwelling Saurida, seem to be only partly correlated with the differences in diet.
- Alimentary tract
- Comparative morphology