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Home / Aquatic Invasives / Aquatic Invertebrates / Colonial Sea Squirt

Colonial Sea Squirt

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Sea squirt
Sea squirt, adult - Photo by U.S. Geological Survey
Scientific Name: 
Didemnum vexillum Kott, 2002 (Stefaniak et al. 2009)
Common Name: 
Colonial sea squirt, ascidian, colonial tunicate, compound sea squirt, carpet sea squirt
Native To: 
Unknown, possibly Japan (Lambert 2009)
Date of U.S. Introduction: 
First confirmed sighting in 1993 (Lambert 2009)
Means of Introduction: 
Introductions likely due to shipping (either via hull or sea chest fouling) (Lambert 2009)
Forms dense colonies that can smother native species (Bullard et al. 2007)
Current U.S. Distribution: 
Coastal New England, Coastal Pacific Northwest



Google. YouTube; Great Britain Non-Native Species Secretariat.

Selected Resources

The section below contains highly relevant resources for this species, organized by source. Or, to display all related content view all resources for Colonial Sea Squirt.

Council or Task Force

Washington State Recreation and Conservation Office. Washington Invasive Species Council.


International Council for the Exploration of the Sea.

See also: Alien Species Alert for more information

San Francisco Estuary Institute; Center for Research on Aquatic Bioinvasions.

IUCN. Species Survival Commission. Invasive Species Specialist Group.
Northeast Aquatic Nuisance Species Panel.
Texas State University System. Texas Invasive Species Institute.
Federal Government

Smithsonian Institution. Smithsonian Environmental Research Center. Marine Invasions Research Lab.

International Government

New South Wales Department of Primary Industries (Australia).

State and Local Government
Alaska Department of Fish and Game.
Columbia University. Center for Environmental Research and Conservation.

University of Alaska - Anchorage. Alaska Center for Conservation Science.