Neomysis americana is an "extremely common" species of opossum shrimp along the Atlantic coast

Atlantic Ocean

The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...

 of North

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

 and South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

. The species has a disjunct distribution

Disjunct distribution

In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but widely separated from each other geographically...

, being present in an area extending from the Saint Lawrence River

Saint Lawrence River

The Saint Lawrence is a large river flowing approximately from southwest to northeast in the middle latitudes of North America, connecting the Great Lakes with the Atlantic Ocean. It is the primary drainage conveyor of the Great Lakes Basin...

 to Florida

Florida

Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...

, and separately in parts of Argentina

Argentina

Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

 (Blanca Bay, Anegada Bay and Samborombón Bay

Samborombón Bay

Samborombón Bay is a bay of Argentina, located at the Río de la Plata's mouth on the Atlantic Ocean. It is about southeast of Buenos Aires. The bay is about long and stretches from Point Piedras in the north to Point Norte, starting point of Cape San Antonio.The bay receives the Salado and...

). There may be a further division within the North American populations between those north of Cape Henry

Cape Henry

Cape Henry is a cape on the Atlantic shore of Virginia north of Virginia Beach. It is the southern boundary of the entrance to Chesapeake Bay.Across the mouth of the bay to the north is Cape Charles...

, Virginia

Virginia

The Commonwealth of Virginia , is a U.S. state on the Atlantic Coast of the Southern United States. Virginia is nicknamed the "Old Dominion" and sometimes the "Mother of Presidents" after the eight U.S. presidents born there...

 (including Georges Bank

Georges Bank

Georges Bank is a large elevated area of the sea floor which separates the Gulf of Maine from the Atlantic Ocean and is situated between Cape Cod, Massachusetts and Cape Sable Island, Nova Scotia ....

) and those from North Carolina

North Carolina

North Carolina is a state located in the southeastern United States. The state borders South Carolina and Georgia to the south, Tennessee to the west and Virginia to the north. North Carolina contains 100 counties. Its capital is Raleigh, and its largest city is Charlotte...

 southwards. N. americana is an important prey item for a number of fish species, including the Atlantic silverside

Atlantic silverside

The Atlantic silverside, Menidia menidia, is one of the most common fish in the Chesapeake Bay and in the Barnegat Bay. It is a common subject of scientific research because has a sensitivity to environmental changes....

, the bluefish

Bluefish

The bluefish , called tailor in Australia, is a species of popular marine gamefish found in all climates. It is the sole species of the Pomatomidae family....

 and the windowpane flounder, Scophthalmus aquosus. Adults typically have a carapace

Carapace

A carapace is a dorsal section of the exoskeleton or shell in a number of animal groups, including arthropods such as crustaceans and arachnids, as well as vertebrates such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron.-Crustaceans:In crustaceans, the...

length of 2.5–4 mm (0.0984251968503937–0.15748031496063 ).