These seaweeds are made up of small, hard segments that are joined
together. They are commonly seen on many of our shores, usually growing
on coral rubble or among living corals, as well as in sandy areas
near reefs. Sometimes forming rather large 'thickets' covering an
area of 40-50cm.
Features: An upright chain of
joined up coin-like flattened segments. Each coin-like segment is
hard as it is impregnated with calcium carbonate. These segments may
be circular or other shapes, some are thick and flat, others thinner
with crinkled or ruffled edges. The portions between the segments
are not calcified, so the 'string' of coins is rather flexible.
A new segment develops from the top and can appear rapidly, within
1-2 days! In some species, the segments are anchored by one large
long bulbous holdfast. In others by a small holdfast of matted filaments,
and yet others in inconspicuous patches of root-like structures emerging
from segments or nodes.
These seaweeds can relocate their chlorophyll (the green pigment used
in photosynthesis). At night, chlorophyll might be concentrated in
the centre of the segment. As a result, the seaweed may appear white.
In addition to calcium carbonate, they also have chemicals that protect
them from herbivores. Despite this, some slugs like the Halimeda
slug (Elysiella pusilla) actually eat the seaweed and incorporates
these chemicals into their tissues to protect themselves!
calcium carbonate released from dead Halimeda seaweeds are
said to make major contributions to sand in some areas such as the
Bahamas and the Great Barrier Reef.
According to AlgaeBase,
there are 60 current Halimeda species.
Big and small coin green seaweed
next to one another
Kusu Island, May 05
A pair of Halimeda
slugs on the seaweed.
Labrador, Mar 05
uses: Some species of Halimeda are used
as fertilizers to recondition acidic soils. They are also
used as animal feed and reportedly have anti-bacterial and
*Species are difficult
to positively identify without close examination of internal parts.
On this website, they are grouped by external features for convenience of
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.
Halimeda discoidea cf.
Halimeda opuntia var.
- 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.
- Chou, L.
M., 1998. A
Guide to the Coral Reef Life of Singapore. Singapore
Science Centre. 128 pages.
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.