Charru mussel

Body contents

Charru mussels can be present at very high densities, reaching close to 100% cover, smothering benthic organisms, and have been observed competing with important aquaculture species for resources. They also attach to vessels, affecting performance and increasing fuel costs.

What to look for

Features:

  • Symmetrical shelled mussel, with an average size of 2.2-5cm
  • Individual mussels have a diversity of external colour schemes from black, brown, grey, orange and (rarely) green
  • M. strigata can be differentiated from similar species by its blueish to purplish opalescent interior and more angled shell valve
  • The species external shell pattern can include zig zags, spots or concentric bands
  • Two, small, obscure teeth present internally of the beak which is generally short and rounded
  • Yellowish flesh covering internal cavity of both shells.
  • Has a pitted resilial ridge along the dorsal margin internally (see Fig. 1)
  • The sculpture on the outside of the shell valves consists of weak concentric striations with fine radial ribs ventrally.
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Fig. 1. 2g for location of resilial ridge (lig), 2h – example of pitted resilial ridge (prr). 2i – anterior margin of shell showing two small teeth (at). (Adapted image from Jayachandran et al.)

Where to look

Look in or around:

  • bedrock
  • rocky reef
  • artificial structures
  • soft sediment
  • on top of other sessile organisms

Likely habitats include:

  • intertidal and shallow waters of estuaries. This mussel can be found in a wide range of temperatures and salinity, generally favouring warmer waters.
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Similar native species

These native species look similar to Charru mussel. They do not need to be reported.

Australian Blue Mussel (Mytilus galloprovincialis planulatus)

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Features:

  • grows larger (typically 5-8cm, but can reach up to 15cm)
  • purplish black shell that is thicker and smoother
  • no pitted resilial ridge along the dorsal margin internally (Fig. 1. highlights a pitted example)

Habitat:

  • found in temperate zones usually in shallow water

Horse Mussels (Modiolus spp.)

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Features:

  • brownish
  • have no teeth anteriorly
  • no pitted resilial ridge along the dorsal margin internally (Fig. 1. highlights a pitted example)
  • commonly have bristles on the outside of the shell

Flea Mussels (Xenostrobus spp.)

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Features:

  • Typically small (to 0.5 cm)
  • blackish
  • have no teeth anteriorly
  • no pitted resilial ridge along the dorsal margin internally (Fig. 1. highlights a pitted example)
  • tends to be found higher up on the intertidal range, further out of the water than most other mussels

Scorched Mussels (Brachidontes spp.)

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Features:

  • have forking radial ridges on the exterior of the shell
  • have no teeth anteriorly
  • no pitted resilial ridge along the dorsal margin internally (Fig. 1. highlights a pitted example)

 

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, for example a coin)
  • contact your state or territory authority.

Report

Stop the spread of marine pests

Start with these simple steps:

  • 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

Check our marine pests map.

The map shows known pests and pests to look for around Australia.

Image of Charru mussel shown against a 5mm scale.

Charru mussel (Mytella strigata)

Not established in Australia

Features: Individual mussels have a range of external colour schemes from black, brown, grey, orange and (rarely) green. The species can display shell patterns ranging from zig zags, spots or concentric bands. Shells have an average size between 2.2-5cm.
Habitat: Tropical and subtropical coastal environments. It generally lives in the intertidal and shallow waters of estuaries and coastal environments, and can be found on a wide variety of surfaces including both hard substrates and soft sediments.
Affects: Native species, aquaculture and shipping. Charru mussels compete for both space and food.
Movement: Vessels, fisheries and aquaculture.