大刺鳅消化道结构及食性研究

Research on Structure of Digestive Tract and Feeding Habits in Mastacembelus armatus

关键词:  大刺鳅  消化道  形态学  组织学  食性

Key words:  Mastacembelus armatus  Digestive tract  Morphology  Histology  Feeding habits

摘要:

为了解大刺鳅(Mastacembelus armatus)消化道结构特点及其功能与食性的关系，以采自东江和桃江水域的大刺鳅为研究对象，采用解剖、石蜡切片、HE染色和胃含物分析等方法，研究了大刺鳅消化道的形态学、组织学结构及食性特征。结果显示，大刺鳅消化道由口咽腔、食道、胃和肠构成；口咽腔具舌、咽骨和咽磨；食道黏膜上皮为复层扁平上皮，含有丰富的杯状细胞，内壁具纵行褶皱和次级分支，肌层由横纹肌和平滑肌共同组成；胃壁和肠壁均由黏膜层、黏膜下层、肌层和浆膜层构成，肌层为平滑肌，分为环肌和纵肌；胃呈“V”型，分为贲门部、胃体部、幽门部3个部分，各部分的肌层厚度相比差异显著(P<0.05)，贲门部向胃体部逐渐增粗，且含有胃腺细胞，幽门部肌层极为发达，形成幽门括约肌；肠较短，具一个弯曲，肠道系数为0.325±0.050，肠绒毛丰富，前肠、中肠和后肠的肠绒毛高度相比差异显著(P<0.05)；胃幽门部和前肠间有2个幽门盲囊。大刺鳅食谱较广，消化道中鉴定出虾类、水生昆虫、鱼类、螺、卵和植物碎屑6大类饵料，摄食时食物不经咀嚼直接吞入；食物多样性指数(H′)为2.19, 不确定性较低，饵料优势指数(D)为0.33，集中性较高；虾类为大刺鳅的主要食物，其相对重要性指数百分比(IRI%)、质量百分比(W%)和数量百分比(N%)分别为97.75%、92.29%和73.07%。研究表明，大刺鳅属肉食性鱼类，其消化道形态和组织学结构表现出与食性相适应的特点，该研究可为大刺鳅人工养殖和饲料开发提供理论参考。

Abstract:

Mastacembelus armatus is primarily distributed in the Yangtze River and aquatic systems in the south of China, and is affiliated with Mastacembelus, Mastacembelidae, and Symbranchiformes. It has great economic value and breeding prospects owing to its high meat quality and balanced nutritional content. However, with overfishing and human influences on its habitat, the population of M. armatus has gradually decreased. We characterized the morphology and histology of the M. armatus digestive tract, aiming to investigate the relationship between the morphological and histological features of the digestive tract and its feeding behavior. Anatomy, paraffin sections, HE staining, and stomach content analysis were used to study samples collected from the Dongjiang River and Taojiang River in Ganzhou, Jiangxi Province. The results indicated that the digestive tract was composed of the oropharyngeal cavity, esophagus, stomach, and intestine. The oropharyngeal cavity contained the tongue, pharyngeal bone, and callous pad. The mucosal surface of the esophagus was covered with squamous epithelial cells, and the inner wall was full of longitudinal folds and secondary branches. The muscle layer consisted of striated and smooth muscles. The gastric wall and intestinal wall were composed of the mucosal layer, submucosa, muscle layer, and serosal layer. The mucosal layer was a single layer of the columnar epithelium, and the muscle layer was a smooth muscle that was divided into circular and longitudinal muscles. The “V-shaped” stomach was divided into the cardia, gastric body, and pylorus. The thickness of the muscular layer in each part was significantly different. There were no goblet cells in the mucosa, but many glands were located in the cardia or body of the stomach. The gastric pylorus muscle layer was extremely developed. There were two pyloric caeca between the stomach and intestine. The intestine had a curve and included three parts: The foregut, midgut, and hindgut. The average intestinal coefficient of M. armatus was 0.325±0.050. There were significant differences among the anterior, middle, and posterior intestinal villi. Nine prey items were identified in the digestive tract of M. armatus, including shrimp, aquatic insects, fish, snails, eggs, and plant detritus. The average percentage of the stomach fullness index was 2.86%. The prey diversity H’ was 2.19, and prey dominance D was 0.33. Shrimp were dominant in the stomach contents, accounting for the relative importance index percentage of 97.75%, numerical percentage of 92.29%, and quality percentage of 73.07%. In conclusion, the histological structure of the digestive system of M. armatus is related to its function and feeding habits. This study provides a theoretical basis for wild resource conservation and nutrition research on M. armatus.