Why are malacostracans important food sources for fish, seabirds, and marine mammals?

Malacostracans are vital to marine ecosystems because they function as essential middle-level converters of organic food energy into animal protein. By consuming a wide variety of organic matter—including detritus, plankton, and decaying plant or animal material—they effectively process energy that is then made available to higher-level predators.12

This role makes them a critical food source for fish, seabirds, and marine mammals. In particular, krill (order Euphausiacea) are highly significant in this regard; they occur in vast swarms and serve as a primary prey species for various fish, birds, and whales, such as the blue whale and finback whale. Because of their abundance and high nutritional value, these crustaceans are fundamental to the stability of marine food chains.13