Their burrowing and feeding affect the aeration, and hence the growth of marsh grasses. They stimulate the turnover and mineralization of important nutrients. They are also a good environmental indicator and sensitive to environmental contaminates especially insecticides. Their population densities are an example of the high productivity of our vital wetlands. Coupled with the crab's role in marsh processes, gives good reason to conserve ecologically important species that are so critical to our own food web.
Fiddler crabs live on sandy and muddy beaches that are uncovered during low tide.
Each crab lives in a hole it digs for itself. The hole can be closed with a mud cap so that, when inside, the crab remains hidden. At low tide, it abandons its dwelling to search for food, but never strays very far unless it is to court some female, or scare away a nosy neighbor. At the slightest danger, it disappears into its hole and doesn't come out for some time. If fiddler crabs become disoriented, they are easy prey for pecking birds.