Devil’s tongue weed

Grateloupia turuturu


Photo credit: David Fenwick
Grateloupia turuturu – Devil’s tongue weed
  • G. turuturu is light to dark reddish-brown in colour with fronds 1-6 forming a small disc; its broadly lanceolate and is generally undivided with undulating margins. It is generally up to 60omm in length (occasionally up to 1m) and is 20-200mm broad. it may produce marginal proliferations, particularly when damaged, and its surface becomes irregular when old. Its reproductive cysticarps appear as dark or black dots.
  • It is found in harbours, marinas, pontoons and inlets, where it favours sheltered habitats. It may be growing in the subtidal zone up to 7m deep, but is a lower intertidal and shallow subtidal species.

Origin and Worldwide Distribution:
  • It is native to the Pacific region around China, Japan, Korea and the far-eastern seas of Russia.
  • It has been introduced to the Pacific coast of Mexico, Australia, New Zealand, the east coast of the United States, France, Italy, the Netherlands, Portugal, Spain, and the United Kingdom.

Potential or Known Impacts:
  • It can outcompete native seaweeds as it can reproduce quickly by sporic and vegetative reproduction.
  • It grows quickly, and in a wide range of environments, including in nutrient-rich waters.
  • It can survive in water with a 12-55 ppt salinity and a temperature range of 4-29ºC.

How did it get here?
  • It was originally confused for other species (e.g. G. doryphora, or G. lanceola) before it was identified through molecular studies.
  • It may have been introduced by commercial shellfish transport, on hull fouling or through sediment movement and water movement.

Is it found in Ireland or Northern Ireland?
  • It is found in Northern Ireland, in Carrickfergus. It is not present in Ireland.

Methods for Prevention:
  • Ensure that it is not spread from already invaded areas.
  • Ensure that equipment is checked, cleaned and dried before putting into another body of water.
  • Report all sightings.

You can help by reporting any sightings:
Invasive Species Ireland

Invasive Species Ireland