Introduced Marine Aquatic Invaders - a field guideJoin the Anti-Pest ProgramMarine pests what are theyHow pests get here What damage they do What we are doing What I can do? Northern Pacific Seastar Green CrabPacific OysterAeolid NudibranchNew Zealand Screw ShellAsian MusselBlack Striped Mussel Chinese ClamEuropean Fan WormJapanese Goby Japanese Seaweed Bryozoan

Aquatic Invaders - Introduced species are a threat to our aquatic biodiversityContacting the Department

Introduced Marine Aquatic Invaders - a field guide

Introducted Marine Species - Bryozoan

Watersipora arcuata

Bryozoan - Watersipora arcuata Photo: Josh Mackie/Museum of Victoria

Australia Invasion

• confirmed invasions in South Australia, Queensland and Western Australia
• unconfirmed sightings in Tasmania, New South Wales and Victoria

Habitat

• encrusting species which attaches to rocks, seaweed and artificial structures such as vessel hulls, jetties, piles and breakwaters
• typically found around low water mark

ID Features

• colonies are flat-encrusting, but some do become bulky and foliose
• colonies may be unilaminar (single layer) or multilaminar
• colonies are dark burgundy with a thin bright red margin
• dark coloured opercula stand out
• zooids in the centre of mature colonies often become black which gives the colony a fringed appearance
• operculum arcs upwards at the proximal (attached) end
• colonies can be very large, up to 30 cm in diameter

More information

More detailed information on this Marine Invader is available here.

...More Information on this Invader

Similar Native Marine Species

Photos: Vicki Barmby/ Museum of Victoria

Watersipora subtorquata

• difficult to distinguish from Watersipora arcuata in the field
• may also be an introduced species
• colonies have a broad orange margin*
• colonies are either flat encrusting or bulky and foliose
• operculum curves down at the proximal (attached) end*

* distinguishing feature

Note: It is difficult to distinguish between Watersipora arcuata and Watersipora subtorquata. As it is possible that both species are introduced, any suspected sightings of either species would be appreciated.

 

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