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Didemnum Vexillum, Carpet Sea Squirt

Didemnum Vexillum, also known as Dvex or Carpet Sea Squirt, is a colonial ascidian thought to originate from Japan. It reproduces and grows quickly and is classed as an invasive non-native species.

What does it look like?

Dvex looks similar to native species but the following characterstics can help with identification. Remember, if you have any concerns that you may have found Dvex please follow the instructions for reporting. Identification posters are also available to download below.

Dvex IDDvex characteristics:

  • Variable growth forms, either flat mat-like sheets or pendulous beard-like growths
  • Uniform colouring, either pale orange, cream or off-white
  • Dvex is not slimy. Its surface is firm and leathery with a veined or marbled appearance
  • On close inspection small open pores can be seen on the surface

Where is it found?

Dvex grows on natural hard substrates and man-made underwater structures down to a depth of 80m. It has been found in many places around the world including the UK. It was first found in Scotland, in the Firth of Clyde in 2009, and was confirmed as present in Loch Creran in 2016.

How is it spread?

Dvex can spread by larvae dispersal and also by fragmentation. It is an offence to spread a non-native species to a new location beyond its native range intentionally or otherwise. There are measures in place to promote biosecurity, reduce the risk of spreading Dvex and advice to marine users to support these measures. 

Please find further information, an identification poster and advice below.

Loch Creran Carpet Sea Squirt Information

Downloadable document:

Title:Didemnum Vexillum
Description:Information and advice on invasive non-native species Didemnum vexillum, carpet sea squirt
File:Loch Creran Carpet Sea Squirt Information Sheet 1 - September 2016 [PDF, 120.4 kb: 12 Apr 2017]
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Loch Creran Carpet Sea Squirt - Biosecurity Action Plan

Downloadable document:

Title:Didemnum Vexillum
Description:Information and advice on invasive non-native species Didemnum vexillum, carpet sea squirt
File:Loch Creran Community Biosecurity Action Plan [PDF, 1926.2 kb: 12 Apr 2017]
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Links to Carpet Sea Squirt Advice and Posters