Ciona savignyi

How will we recognize it?

 Ciona savignyi does not look like any other tunicate in Puget Sound. It has a very soft, nearly transparent body, and is much longer than it is wide. When touched, it quickly contracts, much like a sea anemone.

Left undisturbed, it may extend its two siphons up to three inches or more.

 Ciona savignyi, attached to mussel shells

 Ciona savignyi on test rope
The siphons are ringed with small yellow dots, even on very young specimens. On older animals, white flecks are visible in the tunic.  Looking down the siphon of Ciona savignyi

Where in Puget Sound is Ciona savignyi found now?

Ciona savignyi has been found in these places: 

    • Edmonds
    • Brownsville
    • Eagle Harbor (Bainbridge Island)
    • Des Moines

It appears to be moving rapidly and is likely to appear in other parts of Puget Sound by the summer of 2001. You may be able to report its arrival in new locations.

What impact will it have?

Nobody can predict which invasive organisms will become nuisance species and which will not. We do, however, know some things already about Ciona savignyi, and its close cousin from Europe, Ciona intestinalis, both of which have a history as invasive species. Both species grow abundantly in certain man-made environments, floating docks, boat hulls, and on hanging aquaculture rafts. On natural surfaces they are less common, but C. intestinalis is known to cover eelgrass blades in some Scandinavian Fjords.

Whenever one species begins to dominate an environment once inhabited by other species, it's a sign that important ecological changes are underway. Is the new species now controlling more of the space? Is it consuming more of the food? Is it a new predator on members of the old community? Is it changing some part of the environment in a physical way, by creating more shade or altering water circulation to other organisms? Will the invader cause a native species to become endangered or go extinct? If that happens, what other indirect effects will occur? These questions may take some time to answer---and your experiments may help provide some of the answers.

Map of Puget Sound, showing sites where Ciona savignyi has been found

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