Japanese skeleton shrimp

Caprella mutica


Photo credit: ©Simon Blauenfeldt Leonhard Orbicon and Vattenfall A/S 
Caprella mutica - Japanese skeleton shrimp
  • C. mutica is a pale brown to dark red colour, with males reaching lengths of 50mm and females reaching 29mm. The females also have dark red spots on their brood pouches.
  • The body has seven pereonites (segments); in the male, the first two are elongated. The third to seventh pereonites have dorsal and lateral spines.
  • They are associated with macroalgae in their native range, and man-made habitats outside their native range.

Origin and Worldwide Distribution
  • It is native to Japan.
  • It is now found in Belgium, Denmark, France, Germany, Ireland, the Netherlands, Norway, Russia, the United Kingdom, Canada, the United States and New Zealand.

Potential or Known Impacts
  • It is an aggressive species and will likely displace other native amphipod species by competition for food, shelter and other resources. It also has a high reproductive potential, which means that it can quickly colonise a new habitat.

How did it get here?
  • It may have arrived by hull fouling, contaminated ballast water, or floating debris.

Is it found in Ireland or Northern Ireland
  • It is now found in both Ireland and Northern Ireland.

You can help by reporting any sightings:
Methods for Prevention
  • Ensure that it is not intentionally moved from an invaded area to a non-invaded one.
  • Ensure that equipment is checked, cleaned and dried before using in another body of water.
  • Report all sightings. 
Invasive Species Ireland

Invasive Species Ireland