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Seaweeds > Division Phaeophyta
Sargassum seaweed
Sargassum sp.*
Family Sargassaceae
updated Oct 2015
Where seen? The largest of our brown seaweeds, this golden leafy seaweed with strange air bladders is commonly encountered on our Southern shores, but rarely on our Northern shores. It grows on the rocky shores as well as on coral rubble.

Sargassum bloom over a reef.
Sisters Island, Sep 10
if you learn only 3 things about them ...
Sargassum seaweeds are more common on our Southern shores.
Lots of little animals often hide in them. Look for them!
The little bladders are floats not fruits.
It appears to be seasonal, sometimes forming a luxuriant golden carpet that covers vast areas of the reefs, and washing up on the high tide line in huge heaps. At other times, only short, sparsely bladed specimens are seen, on coral rubble or rocks.

Sargassum is the largest and most plant-like brown seaweed on our shores. The seaweed may have a more permanent (perennial) portion that is usually short and tough, stuck onto hard surfaces. Seasonally, Sargassum blooms, and long 'stems' to 1m or longer may grow rapidly. Attached to the stems are leaf-shaped blades that may be narrow, broad or very small (1-5cm long). There are also small round to oval air bladders (vesicles) interspersed among the 'leaves' are often mistaken for fruits, but seaweeds don't produce fruits like seagrasses do. The sargassum's air bladders help the seaweed stay afloat, closer to sunlight. Thus, long pieces often form floating rafts even after they have broken off from their holdfast. Sargassum may have reproductive structures that look like tiny fingers or other shapes. Some sargassum species can reproduce by producing new plants from horizontal creeping 'stems'. This is an adaptation to living on slippery rocks at the splash zone of rocky shores.

According to AlgaeBase: there are more than 580 current Sargassum species.

Sargassum forest: Sargassum seaweeds are often covered with other tiny seaweeds growing on the blades, while larger seaweeds may be entangled among it. In this tangled forest, all kinds of small creatures lurk, hiding from predator or prey, or both.

Human uses: Sargassum seaweeds are eaten by people, and used fish bait in basket traps, animal feed, fertiliser, insect repellent.

Various species are used as medicine for ailments ranging from children's fever, cholesterol problems, cleansing the blood, skin ailments.

In the tropics, sargassum seaweeds are a significant source of alginates. They are also used as a component in animal feed and liquid plant food or plant biostimulants. Supplies come from harvested seaweeds, the seaweeds are not farmed.

Large piles of sargassum washed ashore.
Sisters Island, Jan 10

Air bladders keep the seaweed afloat
near the water surface and sunlight.
Terumbu Buran, Nov 10

Growing from a hard surface.
Sentosa, Nov 11

Big 'leaves'.

Medium 'leaves'.

Small 'leaves'.

Fluffy bits reproductive structures?

Sisters Island, Feb 06

Long bits reproductive structures?

Labrador, Feb 06

Long bits reproductive structures?

Labrador, Feb 06

Tiny octopus on sargassum.
Sentosa, Jul 04

Tiny Red-nose shrimp
sheltering in sargassum.
Sentosa, Sep 04

Tiny fish and entangled green
seaweed on sargassum.
Sentosa, May 04

Dove snail eats tiny algae
growing on sargassum.

St. John's Island, Sep 07

The Crosslandia nudibranch looks
just like sargassum!

St. John's Island, Jan 06

A Giant reef worm snatches a bunch of
sargassum back into its lair.

South Cyrene, Oct 10

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

Sargassum seaweeds on Singapore shores

Photos of Sargassum seaweeds for free download from wildsingapore flickr

Distribution in Singapore on this wildsingapore flickr map

Pulau Senang, Aug 10

Pulau Senang, Aug 10

Terumbu Salu, Jan 10

Terumbu Berkas, Jan 10

Terumbu Berkas, Jan 10

Terumbu Salu, Jan 10

Pulau Salu, Aug 10

Pulau Biola, Dec 09

Pulau Pawai, Dec 09

Sargassum 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.

  Sargassum angustifolium
Sargassum aquifolium
Sargassum asperifolium
Sargassum assimile
Sargassum baccularia
Sargassum baccularia
var. subcompressum
Sargassum belangeri
Sargassum biserrula
var. singapoorensis
Sargassum brevifolium
var. pergracile
Sargassum cervicorne
Sargassum cinereum
Sargassum filifolium
Sargassum gaudichaudii
Sargassum glaucescens
Sargassum glaucescens
var. ivanii
Sargassum gracile
Sargassum granuliferum
Sargassum granuliferum
var. dubiosum
Sargassum grevillei
Sargassum ilicifolium
Sargassum ilicifolium
var. pseudospinulosum
Sargassum latifolium
Sargassum latifolim
var. sychellense
Sargassum microcystum dilatatum
Sargassum microsystum
Sargassum microphyllum
Sargassum microcystum
var. grandifolium
Sargassum obtusifolium
Sargassum odontocarpum
Sargassum oligocystum
Sargassum oocyste
Sargassum parvifolium
Sargassum plagiophyllum
Sargassum plagiophyllum
var. hebetatum
Sargassum plaigophyllum
var. singapoorensis
Sargassum polycystum
Sargassum pseudocustocarpum
Sargassum pulchellum
Sargassum siliquosum
Sargassum spathulaefolium
Sargassum squarrosum
Sargassum subspathulatum
Sargassum swartzii
Sargassum torvum
Sargassum virgatum
Sargassum vulgare

Links References
  • 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].
  • Lim, S., P. Ng, L. Tan, & W. Y. Chin, 1994. Rhythm of the Sea: The Life and Times of Labrador Beach. Division of Biology, School of Science, Nanyang Technological University & Department of Zoology, the National University of Singapore. 160 pp.
  • 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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