关键词: 裸体方格星虫 , 近海海域, 消化道, 组织结构, Sipunculus nudus, inshore, digestive tract, tissue structure

Abstract: To explore the characteristics of Sipunculus nudus digestive system in near sea area of Zhanjiang, Sipunculus nudus in near sea area of Zhanjiang were selected as materials to observe morphology and histology of the digestive tract. The result showed that Sipunculus nudus digestive system consisted of the mouth, pharynx, esophagus, intestine, rectum, caecum and anus etc. The rectal blind sac attach to the rectum, the digestive tract was about 2.5 times as long as the body, and intestine loop was formed by three folds and spiral winding. The wall of digestive tract is divided into mucosa, submucosa and serous membrane, from inner to outer. Furthermore, there were a lot of creases in the mucosa, without continuous muscle layer, but the submucosa was composed of connective tissue, muscle fibers and nerve and vessel etc. The digestive tract of Sipunculus nudus had developed cilia, rectal blind sac was connect to the terminal rectum and filled with yellow liquid.