About the Data

Species records include data on invasions history, distribution, ecology, impact, and more. These data were gathered from published literature and targeted surveys. All records have undergone expert review, unless otherwise noted.

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Species Profiles

NEMESIS includes detailed information on about 500 species of marine and estuarine of invertebrates and algae introduced to the United States. Each record contains information on taxonomy, distribution, ecology, and impacts, as well as references.

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Daily Invader

Orconectes virilis

Orconectes virilis

Virile Crayfish
The Virile Crayfish is a freshwater crayfish that can tolerate brackish water salinities up to at least 14 PSU. It is native to the Great Lakes, the southern Arctic Ocean, and northern Mississippi drainages from northern Arkansas, Mississippi, and Tennessee to Alberta and southeastern Quebec, with populations extending west in the Mississippi drainage to Montana and Colorado. It has been introduced into at least nine states and the District of Columbia, including California, Washington, Arizona, Pennsylvania, New Jersey, Maryland, Virginia, West Virginia, and North Carolina. It has also been found in New Brunswick, Mexico, England, and the Netherlands. In some parts of its introduced range, it has displaced native crayfish species.

Daily Invader for 2022-08-13

Image Credit Smithsonian Institution, National Museum of Natural History, Department of Invertebrate Zoology via the Encyclopedia of Life CC BY-NC-SA 3.0 License
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