updated Oct 2016
learn only 3 things about them ...
This seagrass is rarely seen on our shores.
It doesn't flower frequently.
is eaten by sea turtles and dugongs.
This seagrass only abundant on Labrador, which has quite a large patch.
On Chek Jawa, it is found in small patches. The preliminary
results of a transact survey of Chek Jawa suggest it is found
mainly in the centre of the seagrass lagoon there. On some of our
Southern Islands, there are also scattered patches of this seagrass.
Sickle seagrass is found throughout the tropical Indo-West Pacific
region. A firmly-anchored seagrass, it can form large beds. It is
found from shallow subtidal areas to 10m and deeper. It does not tolerate
long periods of exposure and does not appear to do well in areas with
Features: The seagrass
has strap or curved, sickle-shaped leaves (0.5-1cm wide and 7-40cm
long, usually less than 25cm). The tips are usually rounded and smooth.
The leaves may appear speckled due to tannin cells that appear red,
purple or dark brown. Those in Singapore often have cross hatching
on the long veins. It has thick rhizomes (underground stems) about
2-4mm in diameter which are white or pink. The rhizomes have air channels
and usually have obvious node scars that are triangular with persistent
leaf sheaths. Shoots emerge from these rhizomes, each shoot with 2-6
leaves encased in sheaths about 3-8cm long.
This seagrass has separate male and female plants. The flowers form
at the base of the shoot and is hidden by the sheath until they emerge.
The male flower is held on a long stalk, maturing into 6 or more parts.
The female flower appears similar but has a finer texture. Fruits
are oval and prickly, containing up to 9 tiny seeds. Some studies
suggest that this seagrass flowers less infrequently than other seagrasses.
It also produces relatively larger fruits.
confused with other ribbon-like seagrasses. Here's more
on how to tell apart ribbon-like seagrasses.
in the habitat: Algae often grow thickly on the leaves,
colouring the leaves white or pink. These are eaten by small grazing
creatures like snails.
the animals that eat this seagrass are dugongs and green turtles.
So it is also sometimes called Dugong grass or Turtle grass.
and threats: It is listed as 'Critically Endangered' on
the Red List of threatened plants of Singapore.
Labrador, Nov 05
Labrador, Mar 06
Cyrene Reef, Oct 07
Tip rounded not
cross-hatching on the long veins.
Cyrene Reef, Aug 11
Pulau Semakau, Apr 08
Cyrene Reef, Mar 07
Labrador, Mar 06
Shorter Sickle seagrass next to
longer Tape seagrass Labrador, Jun 03
Leaves covered with other plants and animals
Labrador, Oct 04
Labrador, May 05
seagrass on Singapore shores
L.J., Yaakub, S.M., and Yoshida, R.L. (2007). Seagrass-Watch:
Guidelines for TeamSeagrass Singapore Participants (PDF).
Proceedings of a training workshop, National Parks Board, Biodiversity
Centre, Singapore, 24th-25th March 2007 (DPI&F, Cairns). 32pp.
- Thalassia hemprichii (Hydrocharitales: Hydrocharitaceae) by Cheok Zi Yu, 2016, on taxo4254.
seagrasses on the Seagrass-Watch website.
G.W. H. and P. K. L. Ng and Ho Hua Chew, 2008. The Singapore
Red Data Book: Threatened plants and animals of Singapore.
Nature Society (Singapore). 285 pp.
- 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.
Michelle (et. al). 2004. A Guide to Tropical Seagrasses of
the Indo-West Pacific. 2004. James Cook University. 72 pp.
H. P. & Menez, E. G., 1997.Field
Guide to the Common Mangroves, Seagrasses and Algae of the Philippines.
Bookmark, Inc., the Philippines. 197 pp.
- Hsuan Keng,
S.C. Chin and H. T. W. Tan.1998, The
Concise Flora of Singapore II: Monoctyledons
Singapore University Press. 215 pp.