
Devil's tongue weed (Grateloupia turuturu) is a red seaweed native to Northwest Pacific. The species has a wide temperature range and attaches to diverse substrates, including boulders, shells, and artificial substrates. Non-native populations exist in Europe, North America (east and west coasts), Brazil, and Australia. The species was first observed on the East Coast of North America in 1994 in Narraganset Bay, Rhode Island. In New York, the first observation of the species was in 2001 in Montauk Point. The species is a recent introduction to New York, and its impacts on the region are currently unknown.
Description
How to identify devil’s tongue weed:
Flat thick blades, size ranging from small leaves to blades up to 3 meters
Blades can have smooth or frilled edges
Grows from a single hold-fast
Gelatinous/slippery texture
Pink to deep red/brown
No mid-rib
Habitat and Distribution

Devil’s tongue weed is native to the Northwest Pacific. It occurs in the low intertidal and shallow subtidal habitats. It attaches to both natural and artificial substrates. Non-native populations exist in Europe, North America (east and west coasts), Brazil, and Australia.
Spread
Devil’s tongue weed was likely introduced through ballast water or ship fouling.
Impacts
The ecological impacts of devil’s tongue weed appear to be localized.
Research from Long Island Sound suggests that devil’s tongue weed may outcompete native algae species and can alter benthic biodiversity. For example, the species may displace native Irish moss (Chondrus crispus) and reduce invertebrate species richness and abundance.
Species Regulation
Devil’s tongue weed is a regulated species under New York State Invasive Species Regulation 6 NYCRR Part 575. Regulated species cannot be knowingly introduced in a free-living state or introduced by means that one should have known would lead to such an introduction, although such species shall be legal to possess, sell, buy, propagate, and transport.
How You Can Help

Clean, drain, and dry your watercraft and equipment thoroughly before visiting other waterbodies.
Inspect and remove debris and mud from boats, trailers, and equipment.
Dispose of all debris and bait in trash cans or at disposal stations.
Drain all water-holding compartments including live wells, bait wells, and bilge areas. If possible, visit a decontamination station and disinfect compartments with hot water (140°F) for at least 30 seconds.
Dry boats, trailers, and all equipment before use in another water body. A minimum of 5–7 days of drying time in dry, warm conditions is recommended.
Do not dump aquarium contents in any waterbodies, drainage ditches, or sewers.
Use certified bait that is non-invasive and disease free.
Learn how to identify Devil’s tongue weed and report any encounters.
If you think you have found Devil’s tongue weed:
DO NOT RELEASE IT ALIVE.
Take several photos of it from different angles and dispose of the specimen.
Email the photos, noting where it was caught (coordinates preferred), to [email protected], OR
Submit a report through iMapInvasives at www.NYiMapInvasives.org
Additional Resources
National Estuarine and Marine Exotic Species Information System - information on marine and estuarine invertebrates and algae introduced to the United States - species profile for Devil’s tongue weed.
Epifaunal and algal assemblages associated with the native Chondrus crispus (Stackhouse) and the non-native Grateloupia turuturu (Yamada) in eastern Long Island Sound – Reseach paper focused on the interactions between a native seaweed and devil’s tongue weed.