The gastric mucosa secretes the inactive enzyme pepsinogen and hydrochloric acid (HCl). In the presence of HCl, the active enzyme pepsin is produced. Pepsin digests proteins into shorter polypeptides. The high concentration of HCl from the parietal cells makes gastric juice very acidic, with a pH of less than 2.he gastric mucosa secretes the inactive enzyme pepsinogen and hydrochloric acid (HCl). In the presence of HCl, the active enzyme pepsin is produced. Pepsin digests proteins into shorter polypeptides. The high concentration of HCl from the parietal cells makes gastric juice very acidic, with a pH of less than 2.
Coral reef. Coral reef, ridge or hummock formed in shallow ocean areas by algae and the calcareous skeletons of certain coelenterates, of which coral polyps are the most important. A coral reef may grow into a permanent coral island.
The Great Barrier Reef is the largest coral reef on Earth. A barrier reef is a long, narrow coral formation that lies parallel to the shoreline of a landmass and is mostly underwater. The Great Barrier Reef is in the Coral Sea, off the northeastern coast of Australia. It extends 1,250 miles (2,000 kilometers) from north to south. In the Coral Sea, off the coast of Queensland, Australia, lies the Great Barrier Reef, one of the natural wonders of the world. A barrier reef is a long, narrow, mostly submerged coral formation that lies parallel to the shoreline of a landmass.