G – Gastrointestinal Tract

Publisher Summary This chapter discusses the gastrointestinal tract in sea mammals. The stomach is a series of compartments starting with the cardiac, fundic, and ending with the pyloric. The boundary of the stomach with the esophagus is determined by the epithelial type; stratified squamous for the esophagus, columnar for the stomach. The distal boundary is marked by the pyloric sphincter. For example, the stomach in pinnipeds is relatively uncomplicated when compared to the rest of marine mammals. The stomach in the California sea lion (Zalophus californianus) consists of a simple cardiac chamber into which the esophagus enters, followed by a narrowing into the pyloric chamber. There is a prominent pyloric sphincter. The pyloric end of the stomach is strongly recurved of the cardiac portion. The parts of the gastrointestinal tract are described in this chapter, starting with the stomach and progressing distally, using the terminology of Chivers and Langer. Also some dimensions are presented, but taking consistent measurements of the gastrointestinal tract, both length and volume, is difficult due to the elasticity of the organs. At death, the muscles lose their tonus and the length and volume can double or triple.