Creeping straggle weed (Gelidium pusillum)

Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help



A cartilaginous, turf-forming red seaweed that is blackish or purplish-red but may be brown or yellow-green in colour. A small plant that grows to 2-10 mm high and is often found in dense mats on rocks developing from a broad creeping base. The thallus is narrow in diameter (0.3-1 mm) with variable branches with spatula-shaped tips. The plant filaments are attached to the rock by colourless rhizoids.

Recorded distribution in Britain and Ireland

Widely distributed and common throughout the rocky shores in Britain and Ireland.

Global distribution



Commonly grows on damp rocks and is found in crevices or under other larger seaweeds such as Pelvetia canaliculata and Fucus spiralis. It is most commonly found in the mid to low littoral zone but may be found in damp conditions on the upper shore or in the sublittoral fringe.  

Depth range

Upper to lower shore

Identifying features

  • Small, 2-10 mm in height
  • Most often red-black in colour
  • Forms a wiry turf like mat
  • Erect flattened spatula-shaped fronds 0.3-1 mm in diameter

Additional information

Identification is difficult due to the lack of distinguishing features and the presence of intermediate forms. Often found mixed within Catenella caespitosa with which it can be confused.  However, Catenella caespitosa has a softer appearance and forms hollow fronds that look like tiny beads.  The worldwide distribution of this species 'needs further investigation' and it may be limited to the North East Atlantic (AlgaeBase, 2015 (cited 2022)). 

Listed by

- none -


  1. Bunker, F.StD.P., Brodie, J.A., Maggs, C.A. & Bunker, A.R., 2017. Seasearch Guide to Seaweeds of Britain and Ireland (Second edition). Plymouth: Wild Nature Press.

  2. Dixon, P.S. & Irvine, L.M., 2011. Seaweeds of the British Isles. Volume 1 Rhodophyta. Part 1 Introduction, Nemaliales, Gigartinales. Exeter: Pelagic Publishing Ltd.

  3. Guiry, M.D. & Guiry, G.M. 2015. AlgaeBase [Online], National University of Ireland, Galway [cited 30/6/2015]. Available from:

  4. Hiscock, S., 1986b. A field key to the British Red Seaweeds. Taunton: Field Studies Council. [Occasional Publication No.13]


  1. NBN (National Biodiversity Network) Atlas. Available from:

  2. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2024-05-18


This review can be cited as:

Mardle, M.J., 2022. Gelidium pusillum Creeping straggle weed. In Tyler-Walters H. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 18-05-2024]. Available from:

Last Updated: 13/01/2022