Without them, dead animals and plants would not decompose into simple compounds that can be used by other organisms. The system would come to a grinding halt, as few of the nutrients locked up in plants would become available. Nematode worms feast on these swarms of bacteria. Each worm species has mouth parts designed for a particular prey. Without the worms, much of the bacterial production could not be transferred to the larger predators at the surface of the mud.
Some biologists believe that nematodes are the most abundant multi-celled animals on earth.
In salt marshes, up to five million nematodes per square metre have been recorded. Biologists also estimate there are more species of nematodes than any other group of organisms. The crustaceans are eaten by juvenile fish and many types of birds. These food chains in the mud distribute the energy captured by plants to all the users of this habitat, and create the great productivity of this ecosystem. The delayed release of energy by these food-webs in the mud provides nutrition for birds and other winter users of the estuary long after the growing season.