11. Function and Importance of Crustaceans

Crustaceans play an important role in the food web, as they are an important link between benthic and pelagic organisms, fish and birds. They are themselves an important dietary component of other invertebrates and for many commercial fish species, such as cod and herring, as well as for those that play a lesser role in the economy. Most are omnivorous, with a broad spectrum of food preferences, thereby contributing to the structure of the ecosystem. Some choose plant food, others are predators, and some are even cannibals. Saduria entomon, Dikerogammarus haemobaphes and Rhithropanopeus harrisii feed on the remains of dead organisms, remove them from the bottom of the water body, thus contributing to the breakdown of organic matter and accelerating mineralization. Species of the genus Gammarus, such as G. salinus, cleanse coastal waters. Some shrimps are used as food for farmed fish. Crangon crangon and Palaemon elegans are used as bait for catching such fish as cod and eels. Ponto-Caspian species like Obesogammarus crassus and Pontogammarus robustoides provide a food source for many species of farmed fish (Photos 11.1 and 11.2).