learn only 3 things about them ...
Agar-agar is extracted from these seaweeds.
Lots of little animals often hide in them. Look for them!
grow rapidly on abandoned rope. In fact, they are farmed
These rather succulent red seaweeds are commonly seen on many of our
shores. On boulders, coral rubble as well as on abandoned ropes, nets
and other objects left on the shore.
Features: Some may form loose
bunches of slender, cylindrical 'stems' about 15-20cm long. Each 'stem'
has a few slender side branches that taper at the tips. Red, brownish
or blackish. Sometimes green.
Others form dense bunch of many slender, cylindrical 'stems' about
5-10cm long. Each 'stem' branches many times into short slender side
branches with tapering tips. Black, maroon sometimes purplish.
According to AlgaeBase:
There are more than 180 current Gracilaria species. The species
are difficult to differentiate based on external features alone. Except
for Knobbly agar-agar red seaweed (Gracilaria
salicornia) with distinctive club-shaped segments.
Some other species found on our shore that resemble Gracilaria include Hydropuntia edulis which also belongs to Family Gracilariaceae
Human uses: The Gracilaria
species are a major source of food-grade agar. The seaweed is both
harvested from the wild and farmed for commercial applications. On
farms, they are grown on ropes. A wide range of Gracilaria species
have commercial uses. About 30,000 tons of Gracilaria species
are produced a year, one-third of this from South America. China was
one of the first countries to cultivate Gracilaria species.
History of agar-agar: Freezing
removes impurities from the agar-agar. According to Japanese folklore,
an innkeeper tossed out some leftover jelly during the winter. This
froze at night then thawed the following day. The innkeeper came across
the resulting white substance several days later. When he boiled it,
he found that it produce a whiter jelly than the original. Thus was
the method of agar production accidentally discovered.
Agar-agar was known in Japan and China for centuries, as a sweetened
or flavoured gel, and was called 'kanten' by the Japanese and 'dongfen'
by the Chinese. It is said that Chinese migrants brought it to South
East Asia. 'Agar-agar' is the Malay name for it, a name which even
the Chinese in South East Asia used. When the Europeans (via the Dutch)
brought it to Europe it was called 'agar'. Thus a Japanese product
came to have a Malay name! In 1882, the use of agar as a medium to
culture bacteria was made famous by experiments on the tuberculosis
Besides Gracilaria, other species used to produce commercial
agar-agar include Ahnfeltiopsis, Gelidium, Gelidiella, Pterocladiella
Many bunches growing on
an abandoned net.
Chek Jawa, Jul 02
Loose clusters of long 'stems'.
Tanah Merah, Apr 05
Denser bunches of short 'stems'.
East Coast, Jun 06
species are difficult to positively identify without microscopic examination.
On this website, they are grouped by external features for convenience
red seaweeds on Singapore shores
|Family Gracilariaceae recorded for Singapore
Pham, M. N.,
H. T. W. Tan, S. Mitrovic & H. H. T. Yeo, 2011. A Checklist of
the Algae of Singapore.
Gracilaria salicornia (Knobbly
Hydropuntia edulis=Gracilaria lichenoides
- 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.
John M. 2000. Marine
Plants of Australia University of Western Australia Press. 300pp.
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.