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Ciona savignyi
Transparent Ciona Tunicate

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!

Ciona Savignyi updates:

  • October 2010: Spotted at Edmonds Underwater Park by Dave Washburn
  • June 2007: Ciona savignyi has mysteriously disappeared at many South Hood Canal sites where large populations were previously found in 2006, and has now popped up in other locations in mass quantities in South Hood Canal.
  • NPR Interview about Ciona savignyi: Listen to the segment online
  • Tunicates in the Times: Warren Cornwall wrote up an excellent article for the front page of the Seattle Times - Feb 20th, 2007. View the online version here.
  • The Kelp Krawlers of Olympia, and the Pacific Dive Club of Aloha Oregon did a HUGE cleanup of Ciona savignyi from Sund Rock in January 2007.
  • A team of volunteer divers with REEF and WSA experimented with removing Ciona savignyi at Sund Rock in Hood Canal (Oct 2006).
  • WSA Volunteer divers also recently surveyed many dive sites throughout Hood Canal to check for presence of the tunicate. (Oct 2006 - ongoing)
  • Georgia Arrow (REEF PNW AAT) first called it to our attention in March of 2006 at Sund Rock in Hood Canal.

How do you pronounce Ciona savignyi?

Sigh-OH-nah sa-VEE-nee or anything close to that!

Where is it found?

It's usually found at depths of 40 feet and deeper, or under covered dock areas in marinas. It doesn't seem to like the light much! We've seen in in several places dwelling at 100 feet. Here's our reports so far:

Hood Canal:

  • Tahuya and Union area (dense shallow mega-populations)
  • Sund Rock (North and South wall - small populations)
  • Jorsted Creek (small deep populations)
  • Rosie's Ravine (small deep populations)
  • Dewatto area (small deep populations)
  • Sponge Hill (deep, about 200ft)
  • Pinnacle (small deep populations)
  • West Wall of Pulali Point (small deep populations)
  • East Wall, Pulali Point (small deep populations)

Puget Sound:

  • Edmonds Underwater Park
  • Eagle Harbor Marina
  • Des Moines marina docks - covered dock areas
  • Redondo Beach in Des Moines
  • Alki (Seacrest Coves 1, 2 and 3)
  • Maury Island Barges

REEF Critterwatchers are being VERY instrumental in reporting the tunicate! Keep up the fantastic work and continue taking photos and reporting your sightings.

Why is the population exploding?

Ciona savignyi feeds on very small particles of sewage and waste, which currently is a problem in Hood Canal due to development and leaking septic systems. It is not known if the low dissolved oxygen problems are contributing to its quick growth. Even with the low DO2 problems, it appeared to be flourishing. It is important to report a sighting early, because once it starts breeding, it can take over an area very quickly.

What does it look like?

  • Clearish, whitish or cream colored
  • Smooth, elongated bodies up to about 6" tall
  • Two siphons with slightly scalloped edges
  • Longitudinal lines at the siphon openings, often with orange dots
  • Small flecks of yellow found on their smooth bodies

Ciona savignyi at Seacrest (Alki Cove 2) in Elliott Bay, Seattle.
On the jackstraw pilings near the wreck of the Honey Bear.
- Photo by Rich Zade

Ciona savignyi grows near Union, on south Hood Canal
- Photo by Georgia Arrow

Ciona savignyi next to Spiny Pink Star. Near Union, on south Hood Canal
- Photo by Janna Nichols

Closeup of longitudinal lines and scallops on edge of siphon.
Also note yellow flecks on body.
- Photo by Georgia Arrow

Ciona savignyi found on Sund Rock's North Wall in October 2006
- Photo by Janna Nichols

What native species might I confuse it with?

There are two native species, Corella inflata and Corella willmeriana, that are also clear tunicates. They are shorter and stubbier, with much shorter siphons, and no flecks of yellow or orange on their bodies. Another possible one that might be confused with it is the Glassy Sea Squirt, Ascidia paratropa. Here's an example of the native species:

Corella inflata - Photo by Richard Zade

Corella willmeriana - Photo by Janna Nichols

Glassy Sea Squirt - Ascidia paratropa - Photo by Janna Nichols

Another thing some divers are confusing Ciona savignyi with is Squid Egg clusters. Squid eggs have pointy ends, no siphons, and if you look closely at them you can see each packet filled with multiple eggs.

- Photo by Janna Nichols

More photos of invasive tunicates are on this website

For more information on Ciona savignyi, visit this website:

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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!