They help stabilize sediments, are food for larger organisms and contribute to an enrichment of the sediments. Rapid changes in salinity, temperature and exposure create stressful conditions and thereby limit how many species occur in this habitat. Fiddler crabs, marsh snails and marsh mussels are typical invertebrate species which live in salt marshes. The popular and highly prized oyster generally borders salt marshes. Fiddler crabs and marsh snails shred dead plant material during feeding, aiding the decomposition process.
Insects are also abundant in the salt marsh.
Most of these salt marsh invertebrates consume living plants, or fluids secreted by the plants. Some insects also feed on detritus, though the importance of their role in the food web as grazers and detritus feeders is small compared to their importance to the abundant species of birds who depend on them for food. The undigested grass eaten by insects is deposited as feces on the marsh surface where it becomes part of the detrital food web. Many fish species living near the salt marsh rely on insects for food during part of the year. Fishes, crabs, and shrimps live in salt marshes where stems, leaves, and roots provide food and shelter from predators.