Introduced Marine Aquatic Invaders - a field guide
Introducted Marine Species - New Zealand Screw Shell
Maoricolpus roseus
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| New Zealand Screw Shell - Maoricolpus roseus Photo: CSIRO Marine Research |
Australia Invasion
- Tasmania, New South Wales, Victoria
Habitat
- temperate to subtropical
- most common in intertidal to subtidal (to 50 metres)
- prefer shell substrate or sandy, muddy substrate
- dead shell often washed up on beaches
ID Features
- large shell to 8 cm in length and 2.5 cm width
- shell has up to 18 whorls and a broadly conical spire
- yellow to reddish brown in colour and faintly marbled with dark brown
- broader than native screw shells
More information
More detailed information on this Marine Invader is available here.
...More Information on this Invader
Similar Native Marine Species
Other gastropods
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| Photo: B Wilson/Australian Marine Shells |
The New Zealand screw shell is a gastropod. There are many other gastropods in Western Australia that superficially may appear similar to it. However, many of these can be distinguished from this introduced species by checking the following features. If you see a shell which:
- has an anterior canal (groove); or
- is less than 6 cm in length or greater than 8 cm in length; or
- has few shell whorls; or
- has sculptured shell whorls;
then it is likely to be a native species.
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| Photo: B Wilson/Australian Marine Shells |
If you see a shell which does not have these features it may be the New Zealand screw shell. As a final check, compare the shell you have found with the other ID features of the New Zealand screw shell described opposite and with the pictures provided.
Note: the anterior canal refers to a groove within the shell opening, not the shell opening itself.
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