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The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.



Didemnum vexillum
Didemnum vexillum
(a colonial sea squirt)
Tunicates
Exotic
Collection Info
Point Map
Species Profile
Animated Map

Copyright Info
Didemnum vexillum
Common name: a colonial sea squirt
Identification: For information on this species, go to http://woodshole.er.usgs.gov/project-pages/stellwagen/didemnum/
Native Range:
Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Didemnum vexillum are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
AK201020101Baranof Island
CA199320108Calleguas; Central Coastal; Mad-Redwood; Monterey Bay; San Francisco Bay; San Francisco Coastal South; San Pablo Bay; Tomales-Drake Bays
DE202320231Chincoteague
ME200220072Passamaquoddy Bay-Bay of Fundy; St. George-Sheepscot
MA199820063Cape Cod; Charles; Gulf of Maine/Bay of Fundy
NH200220071Piscataqua-Salmon Falls
NJ202320231Great Egg Harbor
NY200420041Southern Long Island
OR201020162Coos; Umpqua
RI200020192Narragansett; Point Judith-Block Island
WA199820102Hood Canal; Puget Sound

Table last updated 12/5/2025

† Populations may not be currently present.


 Revision Date: 10/5/2011

 Citation Information:
U.S. Geological Survey, 2025, Didemnum vexillum: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=2776, Revision Date: 10/5/2011, Access Date: 12/5/2025

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.

Disclaimer:

The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2025]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [12/5/2025].

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For general information and questions about the database, contact Wesley Daniel. For problems and technical issues, contact Matthew Neilson.