Hepatopancreas: An organ that plays an important role in shrimp physiology
By Dr. Julia Moh Hwei Zhong
Penaeid shrimps are marine shrimps that have been known to be one of the most important commercial marine species globally. As food security is a huge concern globally at this present time, the farming of penaeid shrimp has grown significantly to meet the increasing global demand for seafood. In fact, there has been a major shift in aquaculture to marine shrimp farming due to the profitability and market value of this sector, with an 86 per cent increase in total production over the last 10 years.
Important commercial Penaeid shrimp species in Malaysia include Black Tiger Prawn (Penaeus monodon), Banana Shrimp (P. merguiensis) and Whiteleg Shrimp (P. vannamei).
Successful cultivation of shrimp often depends on the good health maintenance of the animal in the culture. To ensure healthy growth in shrimp, we must look into their physiological aspects as it has been discovered that improved bodily function subsequently improves the survival of the shrimp in the culture. Thus, improved physiology will result in increased growth and make shrimp more resistant to stress factors such as water quality, pollutants, and pathogens.
One of the ways that the physiological responses of shrimp can be investigated is through the examination of the hepatopancreas. The hepatopancreas is an important organ as it plays a key role in nutrient absorption and storage that will be transported to other parts of the body of the shrimp for the growth of both the body and reproduction. Hence, the function of the hepatopancreas is like the liver and pancreas of mammals where major physiological activities take place, as described below:
Hormone production – Important hormones for shrimp growth and sexual maturation are synthesised in the hepatopancreas.
Digestive system – The hepatopancreas plays a part in digestion and nutrient absorption. The hepatopancreas is where digestive enzymes are synthesised and secreted for digestion of food.
Energy reserves – Lipid are stored in the hepatopancreas as energy reserves that will be used during starvation, moulting and reproduction development (such as ovarian maturation).
Detoxification – The hepatopancreas is also involved in the removal of toxic wastes from the body. Detoxification is also a part of immune response.
Immune response – The innate immune response of shrimp in the elimination of harmful materials such as pathogens is through phagocytosis by the hepatopancreas cells.
The hepatopancreas of a shrimp occupies most of the posterior region of the cephalothorax
The hepatopancreas is also a sensitive organ which means its function is often affected by stress factors such as metabolic changes, moult cycle, nutritional status, disease infection, pollutants, and more. Therefore, the condition of the hepatopancreas is an important indicator of physiological status of shrimp whenever they are exposed to different kinds of stress factors.
The health of the hepatopancreas in shrimp is also important due to the absence of a specialised immune system in the animal. Shrimp do not have adaptive immune systems like those of higher organisms, which means they depend solely on their innate immune response to fight off any pathogens or harmful foreign objects.
One of the ways of improving the immune response of shrimp is by improving their growth performance. It is believed that shrimp withstand stress better with improved growth. Therefore, the effectiveness of their innate immune systems depends on their healthy growth, and to achieve that, they rely on the efficacy of the hepatopancreas in carrying out their metabolic functions.
Aquaculturists can determine the condition of the hepatopancreas through their physical appearance. A healthy hepatopancreas will appear solid, triangular, and brown in colour, while an unhealthy hepatopancreas often appears shrunken and of different colourations. A damaged hepatopancreas will disrupt the normal digestion process, nutrient absorption, and detoxification, which adversely affects the shrimp’s survival in culture.
Hepatopancreas of healthy shrimp are shown in (a) and (b) where they appear solid, large, and brown in colour. (c) and (d) are shrimp infected by Acute Hepatopancreatic Necrosis Disease (AHPND) causing Vibrio parahaemolyticus. The hepatopancreas appears shrunken and pale (almost transparent) (Source: https://doi.org/10.1007/s10499-023-01272-8)
In conclusion, since it is known that the growth and the well-being of shrimp are highly dependent on the health status of the hepatopancreas, some of the ways we can achieve that include the maintenance of good water quality, feeding with sufficient nutrition, and external enhancers such as feed enrichment and culture system improvement (including culture water enrichment and system engineering).
Dr. Julia Moh Hwei Zhong is a lecturer in the Department of Applied Sciences at Curtin Malaysia’s Faculty of Engineering and Science and a researcher at the Curtin Aquaculture Research Lab (CARL) at the campus. She holds a PhD of Science in Aquaculture from Universiti Malaysia Terengganu (UMT), as well as a Master of Science in Aquaculture and Bachelor of Science in Biological Science from the same university. Her research interests include physiology and biology of crustaceans, fish nutrition improvement through natural products, and microbiology, and she has published extensively on these subjects in scientific journals. Her professional associations include being a Member of the Golden Key International Honour Society. Dr. Moh can contacted via email at juliamoh@curtin.edu.my.
