Anatomy of finfish and shellfish

Unit 4 - Gastro Intestinal Tract OR Digestive system and associated digestive glands

4.2.1. Associated digestive glands
Liver
Like other vertebrates, liver is an important organ in fishes which has both “secretary” and “storage” function. This is a large gland in all fishes, but sharks and rays may have extremely large livers comprising about 20% of the body weight especially in some pelagic sharks. The liver usually lies over or partially surrounds the stomach. It is typically bilobed, but may have only one lobe as in salmon or three as in mackerel. In Hag fishes the liver is in two distinct parts, with separate ducts leading to the gallbladder. Adult lamprey have no bile ducts or gall bladder, gall bladder is also absent in burbot (lota) but in most other fishes the gall bladder is present and function to store liver secretions. Ordinarily one hepatic ducts originates from each lobe of the liver and joins the cystic ducts from the gall bladder to form the “bile ducts”
Liver function includes bile secretion and glycogen storage in addition to several other biochemical processes. Apart from their function fish liver also stores fats, vitamin “A” and “D” and the weary RBCs releasing hemoglobin for recycling into the body liver also helps production of urea and other nitrogenous compounds.