 Dear students, in this topic we shall discuss the stomach which is a storage part of the foregut. The major functions of the stomach are, it acts as the major storage organ of the foregut. It also carries out initial stages of protein digestion. It secretes an enzyme pepsin in its inactive form pepsinogen in an acidic environment which is produced by the secretion of hydrochloric acid or HCl. Stomach has a major function, mechanical treatment of the food which involves grinding of the contents of food with the muscular contraction of its walls. Grinding it also mixes the food with digestive juices, vertebrates stomachs which are based on the number of chambers of stomach. Stomachs may be monogastric stomachs or digastric stomachs. Monogastric stomachs consist of a single strong muscular tube or sac. For example, the stomachs found in carnivores and omnivores. Digastic stomachs multi-chambered hote. They are found in ruminant mammals belonging to the order RTO Dectila. For example, deer, giraffe, sheep, cattle, camel and llama have digastric multi-chambered stomachs. Digastric stomachs have two major divisions. In hard division, they have two two chambers. Overall, they have four chambers, but two divisions. First division has fermentation chambers which are called roman and reticulum. Whereas, in the second division, they are omeasome and eb omeasome. Fermentation chambers go true stomach which is basically secretory. First, we shall discuss the fermentation chambers roman and reticulum which receive the food or vegetation after grazing. These chambers act as fermentation chambers. These chambers have a large population of bacteria and protozoans. These microbes ferment the carbohydrate components of the ingested food and cause their extensive digestive breakdown. Omeasome or eb omeasome, the omeasome is secreted by the digestive enzymes characteristic of the stomach and also digests some protein part of the food. Dear students, birds' stomach is multi-chambered. It has two chambers. These two chambers are called proventiculus or ventriculus. Proventiculus is actually the true stomach which has a secretory function. Whereas, ventriculus is also called gizzard. It is the muscular stomach. Proventiculus is secretory and gizzard has highly muscular grinding chambers. These gizzard have sand, pebbles or stones which remain in it due to swallowing. These stones help in grinding off seeds and grains. Some fishes, insects and decapote crustaceans' stomachs are also variations of the birds' pattern.