Internal
Gastrointestinal Tract of the Dogfish Shark
Key
1.
Papillae of esophagus
2.
Rugae of Stomach
3.
Stomach
4.
Vulvular Intestines
5.
Position of Anus
6.
Rectum
7.
Spiral Valve
Papillae line the lumen of the esophagus, and rugae line the lumen of the
stomach. The rugae allow the stomach to expand, thus permitting the shark
to overfeed. The rugae in this shark are not easily seen because the shark
had just recently eaten. Spiral valves are readily apparent in the lumen
of the intestines. Their purpose is to increase surface area.
