Common Name
Didemnum tunicate (sea squirt)
Scientific Name
Didemnum species
Status
Not yet present in Cape Breton waters
Description
- A genus of invasive sea squirts
- Colonial sea squirts
- When in large colonies, they form lobed or mat-shaped structures
- Zooids are connected by a membrane (the ‘tunic’)
- Color is highly variable and ranges from tan to orange or yellow
- only one siphon visible (the excurrent siphons collect together and excrete into a chamber for collective release of wastes)
- Groups of zooids may be separated by dark lines
- May have a spotted appearance
- Larvae settle within minutes to hours
- Can develop new colonies though fragments
Invasion History/Regional Sightings
These sea squirts have not yet invaded the Maritime Provinces. These species of sea squirts can be found on the Pacific coast of the United States and Canada with the Atlantic coast being at risk to invasions. In 2003, researchers found what is believed to be Didemnum vexillum on the northern edge of Georges Bank. It has formed dense mats and scientists continue to monitor the growth of this colony.
Additional websites for Didemnum species
- Identification card for Didemnum sp. - Salem Sound Coastwatch
- Great pictures and information - from the Exotic Species Guide of San Francisco Bay
- Marine Nuisance Species - Didemnum sp. - From the U.S. Geological Survey
- Information on Didemnum sp. - from the Global Invasive Species Database
- Research on Didemnum sp. on George's Bank - USGS Marine Nuisance Species website
- Additional information about Didemnum sp. on George's Bank - USGS
- Magazine/newsletter story about Didemnum on George's Bank - National Oceanographic and Atmospheric Administration, USA
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