Species description: A dark red to almost black seaweed, native to the NW Pacific, that can form large mats. They can either grow in a bushy form or be more long and straggly in shape. It has long, slender, irregularly branched fronds and is usually around 30 cm in length, but has been recorded as being able to grow as long as 2 m. Branches are cartilaginous, and circular or almost circular in cross-section, and may feel elastic due to hollow sections. The holdfast is a very small disc.

Habitat: Seems to prefer sheltered, muddy habitats such as harbours and bays. Has been reported to tolerate variable salinity and to be able to colonise estuarine environments.

Distribution: Scattered records from around Britain and Ireland. First recorded from Dorset, England, and mostly recorded in marinas and harbours or areas with heavier boat traffic/movement. Any new records should be reported.

Similar Species: Could be confused with other thinly branching red algae, especially Gracilaria gracilis. Expert identification may be required.

Key Identification Features:

• Long, irregularly branched fronds.
• Very small disc holdfast.

Distribution Map from NBN: Gracilaria vermiculophylla at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Gracilaria vermiculophylla at iNaturalist World Species Observations database.

WoRMS: Gracilaria vermiculophylla at World Register of Marine Species. Accepted name: Gracilaria vermiculophylla (Ohmi) Papenfuss, 1967. AphiaID: 236157.

Classification: Biota; Plantae; Biliphyta; Rhodophyta; Eurhodophytina; Florideophyceae; Rhodymeniophycidae; Gracilariales; Gracilariaceae; Gracilarioideae; Gracilarieae; Gracilaria