NAS - Nonindigenous Aquatic Species

small fish


NAS logo - click to go to the NAS home page Tunicates, also called sea squirts, (Phyum Chordata, Subphylum Urochordata) have all the characteristics of a chordate but lack a backbone, so they are invertebrates. The are usually found in marine environments, but a few species are found in fresh water. Some species of tunicates are colonial while others are solitary. Tunicates go through a free swimming larval stage before settling on the substrate. Standard methods of introduction include ship fouling or transportation in ballast water of ocean-going vessels. Potential impacts include competition with native species for suitable substrate and effects on organisms to which they attach. An example of an introduced tunicate is the club tunicate, Styela clava (pic 42k). This species was introduced into Newport Harbor, California, in the 1920s, where it went unnoticed until 1933. By 1949, it was one of the two dominant tunicates in the bay. It has replaced the native solitary tunicates in the bay.
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Data Queries and Species Lists

Tunicate picture Data Queries
Species List of Nonindigenous Tunicates
(links to factsheets and collection information)

Links to News and Other Information

Charles and Gretchen Lambert's Tunicate Page
Exotics in Monterey Bay National Marine Sanctuary
Invasive marine species found on Georges Bank (NOAA)
Ascidians of the West Coast of North America (Image Gallery)

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