''Palaemon vulgaris'', variously known as the common American prawn, common grass shrimp, marsh grass shrimp or marsh shrimp, is a common species of

shrimp A shrimp (: shrimp (American English, US) or shrimps (British English, UK)) is a crustacean with an elongated body and a primarily Aquatic locomotion, swimming mode of locomotion – typically Decapods belonging to the Caridea or Dendrobranchi ...

in the western Atlantic Ocean from

Cape Cod Bay Cape Cod Bay is a large bay of the Atlantic Ocean adjacent to the U.S. state of Massachusetts. Measuring below a line drawn from Brant Rock in Marshfield to Race Point in Provincetown, Massachusetts, it is enclosed by Cape Cod to the south ...

to the

Gulf of Mexico The Gulf of Mexico () is an oceanic basin and a marginal sea of the Atlantic Ocean, mostly surrounded by the North American continent. It is bounded on the northeast, north, and northwest by the Gulf Coast of the United States; on the southw ...

. Adults grow to less than long, and are transparent except for some orange pigmentation on the

eyestalk In anatomy, an eyestalk (sometimes spelled eye stalk and also known as an ommatophore) is a protrusion that extends an eye away from the body, giving the eye a better field of view. It is a common feature in nature and frequently appears in fict ...

Hydrodynamics

Marsh grass shrimp have been investigated for their maneuverability and swimming. These shrimp swim metachronally, creating an appendage wave, starting with the

pleopod The anatomy of a decapod consists of 20 body segments grouped into two main body parts: the cephalothorax and the pleon (abdomen). Each segment – often called a somite – may possess one pair of appendages, although in various groups these m ...

closest to the tail, beating all of their appendages with a phase lag. They also modulate the profile area of their appendages to create net thrust. Through

Particle Image Velocimetry Particle image velocimetry (PIV) is an optical method of flow visualization used in education and research. It is used to obtain instantaneous velocity measurements and related properties in fluids. The fluid is seeded with tracer particles whic ...

two drag-reducing mechanisms
have been identified in marsh shrimp swimming that enable them to reduce drag during the return stroke of their beat. The first of those mechanisms is asymmetric flexibility, with the appendages staying mostly rigid during the power stroke and being flexible during the return stroke, this results in a reduced wake. The second of those mechanisms is grouping of the appendages.Tack, Nils, and Monica M Wilhelmus. "Swimming isn't such a drag: How the coalescence and flexibility of shrimp pleopods minimize drag during metachronal swimming." ''Bulletin of the American Physical Society'' (2022).

References

Palaemonidae Caridea of the Atlantic Ocean Crustaceans described in 1818 {{Caridea-stub