Hemimysis (Bloody Red Shrimp)

Bloody Red Shrimp

NOAA Great Lakes Environmenta Research Archive, Bugwood.org – See more at: http://www.invasive.org/browse/detail.cfm?imgnum=5431273#sthash.U1nh0qxt.dpuf

Bloody red shrimp (Hemimysis anomala), are an invasive crustacean in the Mysidacea order native to freshwater areas in Europe and western Asia. They been detected in all of the Great Lakes except for Lake Superior and were likely brought here by the ballast water of ships. The first sighting of this species in Lake Ontario was in 2006. Later that year the shrimp were found near Oswego, New York. Populations of this species grow quickly and can be found at high densities; 500 shrimp per cubic meter in some locations.


Currently, the impacts of Hemimysis are not well understood. However, because they eat tiny plants and animals such as plankton and insect larvae, there could be impacts on the native food chain. Specifically, food availability may be reduced for young native fishes.


Size: Mature bloody red shrimp reach 6-13 millimeters in length; females are slightly larger than males.

BRS body

Color: the species can be ivory-yellow in color or translucent, but have red pigmentation on their dorsal and posterior section.  This pigmentation is thought to be associated with their semi- nocturnal behavior, and varies in a response to light and temperature conditions. In shaded areas, individuals tend to have a deeper red color.

Juveniles: are more translucent in color than adults.

Distinguishing features: bloody red shrimp can be distinguished from other mysid species, such as the opossum shrimp, by comparing the posterior section (telson) which in bloody red shrimp has a long spine at both corners compared to the forked telson of opossum shrimp.


During daylight hours especially during the summer, bloody red shrimp may be observed in red colored swarms along the shadowed edges of piers, boats, or shorelines.



Bloody red shrimp have a history of invading canals, streams, lakes and reservoirs throughout Europe; therefore they are considered a ‘high risk’ invader of inland lakes in the Great Lakes region. It is vital for the prevention of their spread that all watercrafts and equipment be clean, drained and dried before and after every visit to a body of water. To review the proper precautions visit the Stop Aquatic Hitchhikers Campaign at www.protectyourwater.net

Photo Credits: Title photo: S. Pothoven, (NOAAGLERLgov).  Identification and swarm photo: Great Lakes Aquatic Non-indigenous Species Information System (NOAAGLERLgov). Posterior photo: watershedcouncil.org. 

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