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Seaweeds > Division Rhodophyta
Encrusting coralline red seaweed
Family Corallinaceae
updated Sep 2019

Where seen? Thin pink layers of these algae are commonly seen encrusting stones, coral rubble and other hard surfaces, especially on our Southern shores.

Features: This algae covers hard surfaces in a thin, hard slow growing layer. It grows on things like stones, coral rubble, litter such as discarded bottles and washed up pieces of wood. It even coats the shells of living snails and shells occupied by hermit crabs. As well as seagrass leaves. The algae incorporates calcium carbonate and is hard and stony. It is thus also called encrusting calcareous algae. Colours from rose pink, salmon to pale pink and purplish. May be white when bleached.

Encrusting pinkish seaweeds may belong to several groups including: Mesophyllum from Family Hapalidiaceae and Hydrolithon species from Family Corallinaceae.

Role in the habitat:
By growing over bits and pieces, this seaweed is literally the cement of the reef, stabilising the reef structure. Thus providing shelter for reef dwellers. This role is especially important in places where the currents or wave action are too strong for hard corals to grow well. In such places, coralline algae fortify and reinforce the reefs, reducing erosion.

Although they don't look very tasty, some young animals such as lobsters may eat a great deal of coralline algae.

Coralline algae are also thought to induce settlement and recruitment of invertebrates. Studies suggest young abalones, some corals and soft corals prefer to settle in areas where coralline algae can be found.

There are also suggestions that the presence of coralline algae suppresses the growth of other kinds of seaweeds which may otherwise smother a reef.

Elsewhere, some species can grow unattached (called rhodoliths) forming extensive localised beds, made up of thousands of individuals.

Encrusting dead coral.
Sentosa, Jun 05

Coralline algae on the shell of a living snail
Sentosa, Aug 04

Encrusting a Hammer oyster.
Pulau Semakau. Feb 09

The whitish stuff that grows on seagrass leaves
is probably also coralline algae
Labrador, Oct 04

Encrusting seagrasses.
Sentosa, Oct 08

*Seaweed species are difficult to positively identify without microscopic examination.
On this website, they are grouped by external features for convenience of display.

Encrusting coralline red seaweed on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores

Lazarus Island, Feb 11

Sisters Islands, Jan 10

Sisters Islands, Jan 10

Pulau Senang, Aug 10

Terumbu Bemban, Jun 10

Pulau Pawai, Dec 09

Hydrolithon species recorded for Singapore
Pham, M. N., H. T. W. Tan, S. Mitrovic & H. H. T. Yeo, 2011. A Checklist of the Algae of Singapore.

  Hydrolithon farinosum

Mesophyllum species recorded for Singapore
Pham, M. N., H. T. W. Tan, S. Mitrovic & H. H. T. Yeo, 2011. A Checklist of the Algae of Singapore.

  Mesophyllum erubescens



  • Lee Ai Chin, Iris U. Baula, Lilibeth N. Miranda and Sin Tsai Min ; editors: Sin Tsai Min and Wang Luan Keng, A photographic guide to the marine algae of Singapore, 2015. Tropical Marine Science Institute, 201 pp.
  • Pham, M. N., H. T. W. Tan, S. Mitrovic & H. H. T. Yeo, 2011. A Checklist of the Algae of Singapore, 2nd Edition. Lee Kong Chian Natural History Museum, National University of Singapore, Singapore. 99 pp. Uploaded 1 October 2011. [PDF, 1.58 MB].
  • Harvey, A.; Woelkerling, W.; Farr, T.; Neill, K.; Nelson, W. (2005) Coralline algae of central New Zealand: an identification guide to common crustose species (pdf). NIWA Information Series No. 57 on the New Zealand National Institute of Water and Atmospheric Research website
  • Chou, L. M., 1998. A Guide to the Coral Reef Life of Singapore. Singapore Science Centre. 128 pages.
  • Huisman, John M. 2000. Marine Plants of Australia University of Western Australia Press. 300pp.
  • Calumpong, H. P. & Menez, E. G., 1997.Field Guide to the Common Mangroves, Seagrasses and Algae of the Philippines. Bookmark, Inc., the Philippines. 197 pp.
  • Trono, Gavino. C. Jr., 1997. Field Guide and Atlas of the Seaweed Resources of the Philippines.. Bookmark, Inc., the Philippines. 306 pp.
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