Ciona intestinalis (Vase tunicate)

Animal Tunicate/Sea-squirt
Family: Cionidae
Classification: Unlisted Invasive Species

State aquatic managers ask the public to report sightings of tunicates and other aquatic invasive species. To report sightings contact:

Allen Pleus
A quatic nuisance species coordinator for WDFW
(360) 902-2724

Pam Meacham
WDFW Assistant aquatic nuisance species coordinator
(360) 902-2741


Ciona intestinalis is a solitary tunicate (“sea-squirt”) whose native range in unknown but suspected to be Northern Europe.  It is not considered native to the Pacific Northwest.  C. intestinalis is whitish in color to almost clear.  In fact, it can be so transparent that the organs can be seen within.   It is generally vase or tube-shaped, slightly thicker near the attached base.  Five longitudinal muscle bands are visible along the length of the skin.  It has two siphons that bear bright yellow margins with small red spots on the rims.  C. intestinalis can be found in tidal waters to depths of over 1000 feet, but can also be found under cover in protected waters on hanging aquaculture rafts, in marinas under docks, pilings, boat hulls and other structures and is very tolerant to water pollution. C. intestinalis can form dense aggregations groups or clusters that aggressively compete with many other organisms including mussels and oysters for food and space.

C. intestinalis pumps water in through the inhalant siphon, filters out oxygen and feeds on small organisms such as phytoplankton, zooplankton, oyster and mussel larvae, and other suspended organic materials, and then pumps the water as waste out through the exhalent siphon.  The siphons are able to retract when the animal is disturbed.

Like all sea squirts, C. intestinalis is hermaphroditic, meaning that it contains both male and female organs.  However the male and female parts of each individual do not mature at the same time, so it does not self fertilize.  Eggs and sperm are broadcast spawned into the water column producing planktonic, tadpole-like, larvae that can survive for only a few days unless a suitable substrate is found to attach to.  It then metamorphoses into an adult that can reach up to 6 inches in length.

See the Tunicate information page for more information.

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