Body contents
Carpet sea squirt (Didemnum vexillum) grows over and smothers native marine species such as shellfish, sea sponges and algae. It covers artificial structures, such as jetty pylons, pontoons, buoys, vessels and aquaculture stock and equipment. It can also cover hard natural surfaces, such as bedrock, cobble, oysters and reef. Carpet sea squirt has been detected in both Western Australia and New South Wales.
What to look for
Features:
- yellow grey mass (but colour can vary)
- covered with holes that siphon water
- grows fast and aggressively
- larger specimens (over 10-20 cm) can vary from encrusting forms to animals that produce ‘arms’ or tendrils up to 1m long hanging below the main mass.
Where to look
Look in or around:
- artificial structures, such as wharves, jetty pylons, pontoons and buoys
- natural substrate, such as bedrock, cobble, oysters and reef
- aquaculture stock and equipment
- intake pipes
- vessels, including hulls and niche areas.
Likely habitats include:
- hard artificial and natural surfaces
- estuaries and marine waters from low tide mark to 80 m deep
- cold to sub-tropical waters between 0 to 31 °C.
Similar species
Both native Didemnum species and the invasive colonial sea squirt (Didemnum perlucidum) may look similar to carpet sea squirt. The only way to be certain of identification is through expert identification or molecular techniques.
Colonial sea squirt (Didemnum perlucidum)
Features:
- typically an iridescent white or light grey, but can vary from grey/brown to an orange tinge in colour
- many small individual sea squirts (<2 mm long) make up colonies
- colonies can be many cm in size to larger groups with drooping ‘arms’ or tendrils.
Habitat:
- hard artificial and natural surfaces
- high tide to sub-tidal waters
- water temperatures between 17 to 32 °C.
Colonial sea squirt is established in Australia. Known locations are Western Australia, Northern Territory and Queensland. Suspected detections of colonial sea squirt should be reported.
Report it
See something unusual? Report it. Even if you’re not sure.
If you see something you think is a pest:
- note the exact location (screenshot your map app or enable photo geotagging on your phone)
- take a photo (use something for size reference, like a coin or note)
- contact your state or territory authority.
Stop the spread of marine pests
Start with these simple steps:
- Check anchors and other equipment for tangled algae.
- Inspect and clean your boat or yacht. Make sure you check hard to reach areas.
- Treat the hull of your boat or yacht regularly.
- Clean and dry your fishing and diving gear after every use.
How you can stop the spread of marine pests.
Your location
The map shows known pests and pests to look for around Australia.
