
Dead man’s fingers/ Green fleece (Codium fragile) is a green seaweed native to Asia that is now present throughout the globe. The species was first observed in New York in 1957. The species can have negative ecological and economic impacts.
Description
How to identify dead man’s fingers/green fleece:
Bright green
Spongy round branches
Branches have short hairs that give the algae a felt like appearance
Attaches to hard substrates
Habitat and Distribution
Green Fleece is a green seaweed to Asia that is now present throughout the globe. The species occurs in low intertidal and subtidal habitats and attaches to natural and artificial substrates. Green fleece can occur in variety of habitats including rocky shorelines, seagrass beds, oyster reefs, marinas. In New York, the species was first reported in 1957 in Orient Harbor.
Impacts
The impacts of the species vary throughout its non-native range.
Economic: The species can be a nuisance for the shellfish industry, attaching to shellfish, smothering them, or carrying them away.
Ecological: Dead man’s fingers may also outcompete native algae. However, this change may not always be negative, as green fleece can also serve as habitat for other species. In Long Island, green fleece may be replacing lost eelgrass beds and could potentially serve as a predation refuge for bay scallops.
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 shore crabs and report any encounters.
If you think you have found Green Fleece:
DO NOT RELEASE IT ALIVE.
Take several photos of it from different angles and then throw it in the trash.
Email the photos, noting where it was caught (coordinates preferred), to [email protected], OR
Submit a report through iMapInvasives
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 green fleece
Comparative survival of bay scallops in eelgrass and the introduced alga, Codium fragile, in a New York estuary – research paper determine if dead man’s fingers is a suitable alterative habitat to eelgrass for bay scallops in New York