European Green Crab (Carcinus maenas)

About

This crab varies in colour a lot and looks similar to other native species although is an invasive crab listed amongst the 100 most damaging intruders in the world coming in at number 18. It is an aggressive feeder and can outcompete native species for food, now widespread and common species in Tasmania and considered naturalised. Unfortunately this means there is little that can be done to remove this crab as it's range expands around the world.

Believed to have been introduced in Australia a century ago in dry ballast it has since spread across the southern states, Tasmania, Victoria and South Australia.

Locally it is common along Tomahawk Beach, West Tomahawk Beach and Waterhouse Conservation Area, from beachcombing to foraging through rock pools you are sure to come across this species.

Similar Species include Ovalipes australiensis, Nectocarcinus integrifrons, Nectocarcinus tuberculosus

Identification

To identify this crab look at the shape of the carapace in particular look at the notches or anterolateral teeth (the triangular shaped spines) to the outside of the eyes, there needs to be 5 teeth and the last leg does not have a swimming paddle it is pointed rather than rounded. The images below are to help show you these features

Size

Can grow up to 70mm across the carapace, although larger specimens have been found up to 100mm

Habitat

This versatile crab can survive in many environments from low salinities of around 4% up to around 52% and temperature ranges from 0 to 30 °C. Locally it is found along shore lines and estuaries under rocks and shore debris

Distribution

Native to European and North African coasts, in Australia it is found from NSW to South Australia including around Tasmania

How to Identify

There needs to be 5 teeth and the last leg does not have a swimming paddle

To identify this crab, examine the shape of the carapace, especially the notches or anterolateral teeth (the triangular spines located near the eyes). There should be five of these teeth. Additionally, note that the last leg is pointed rather than rounded, lacking a swimming paddle. The images below illustrate these features for reference.

There are other features such as the shape of the frontal region however the above two characteristics are the easiest to spot colour also varies greatly from pale greenish whites to greenish browns depending on age of the crab.