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Invasive Tunicates
in Washington State

Tunicates Home | Ciona savignyi | Styela clava | Didemnum vexillum
Report a sighting to WDFW: (360) 902-2700
Don't forget to report it on your survey form too!
Club Tunicate
Styela clava
Photo by Janna Nichols
Transparent Ciona Tunicate
Ciona savignyi
Photo by Janna Nichols
Invasive Didemnum
Didemnum vexillum
Photo by Gretchen Lambert

NPR/KUOW spot - May 2008 - by reporter/local diver Ann Dornfeld

Warren Cornwall wrote up an excellent article for the front page of the Seattle Times - Feb 20th, 2007. View the online version here.

What's a tunicate?

Commonly called "Sea Squirts" and part of the group called Urochordates, tunicates are a group of marine animals that appear to be shaped much like a blob or a tube, with two siphons in the top, and an outer covering called a tunic. They can be small to medium sized, and can be solitary or live in colonies. Although they appear to be a simple creature, they're actually quite complex on the inside, and are more closely related to humans than any other marine invertebrate. The Pacific NW is home to several species of native tunicates. But they're not the problem...

What's the problem?

Some tunicates, called Invasive Tunicates, can find their way from other parts of the world to our local waters - Puget Sound and Hood Canal - and have no natural predators here. They can reproduce quickly and can crowd out or kill populations of local native marine species. There is a growing concern that Washington's shellfish industry may be affected.

How do they get here?

In spite of Washington State Law, ballast water from container ships occasionally is illegally discharged into Puget Sound and may contain larvae of potentially harmful species originating from other parts of the world. However, while this may be the pathway for many invasive species, it's not likely that this is how invasive tunicates have come to our area. Another method of introduction is through imported shellfish stock. It is likely that some Invasive Tunicates, specifically the ones plagueing south Hood Canal, arrived in our local waters through this method.

How can I help?

The Puget Sound Partnership and other government agencies are anxious to determine how widely these tunicates have spread in Puget Sound and Hood Canal, and if there might be a chance to control them before they take a firm root in our waters. We are asking all recreational divers to keep an eye out for them and then report it! Early efforts to isolate and treat tunicates in the Pacific Northwest have been very effective, and prompt action is critical!

Can you show me how to identify them?

But of course!

Tunicates Home | Ciona savignyi | Styela clava | Didemnum vexillum
Report a sighting to WDFW: (360) 902-2700
Don't forget to report it on your survey form too!