learn only 3 things about them ...
Spoon-shaped seagrasses come in a range of sizes. Some
scientists treat them as a complex of one species.
They don't flower frequently, and the flowers are tiny.
are believed to be among the favourite food of dugongs.
This small oval seagrass is commonly seen on many of our shores in
the North and South. Sometimes, they may form lush meadows, at other
places, smaller patches. The preliminary
results of a transact survey of Chek Jawa suggest it is probably
among the most widely distributed seagrass in the seagrass lagoon
Spoon seagrass is found throughout the tropical Indo-West Pacific
region and even in some parts of temperate Australia. This seagrass
has one of the widest tolerance. It is found from shallow subtidal
areas to the deepest waters where seagrasses can be found, 30m and
deeper. It can tolerate areas with freshwater runoff and thus lower
salinity, as well as hypersaline waters.
Features: The seagrass
has oval, spoon-shaped leaves and is sometimes also called 'paddleweed'
or fan seagrass. It comes in a wide range of sizes (0.5-1.5cm wide
and 0.5-2.5cm long) and shapes from oval, to nearly oblong or spoon-shaped.
The leaf edge is smooth with no serrations, there is a vein just within
the leaf margin (intramarginal vein). The leaf has obvious cross veins
(4-25) and is held on a long thin stalk. It has thin, smooth, white
rhizomes (underground stems) about 2mm in diameter. The leaves emerge
in pairs from these rhizomes. The emerging shoot is encased in a pair
of transparent scales.
Sometimes confused with seaweeds
that are also spoon-shaped such as the Coin
seaweed (Halimeda sp.) and Fan
seaweed (Avrainvillia sp.). These seaweeds don't have veins
like the spoon seagrass. Coin seaweeds are also hard as they incorporate
calcium in their body structure, while spoon seagrass blades are soft
Flowers and fruits: Spoon seagrass
has separate male and female plants. The flowers form at the base
of the shoot but may extend to above the height of the leaves. The
male flower remains low. The round fruits are tiny. In Australia this
seagrass is reported to flower densely with lots of seeds setting.
Several species of seagrasses look very similar and are difficult
to distinguish from Halophila ovalis. These include H. minor,
H. ovata and H. hawaiiana. There is some uncertainty whether all
these seagrasses are actually distinct species and some scientists
treat them as one species called Halophila ovalis 'complex'.
H. ovalis and H. minor are recorded for Singapore.
Role in the habitat: This seagrass
is among the favourite food of dugongs so it is also sometimes called
Dugong grass. Studies suggest that Halophila ovalis can recover
rapidly from grazing by dugong. The seagrass leaf provides a surface
for small algae to grow on. Tiny snails graze on this algae. These
in turn are eaten by larger creatures. In this way, seagrasses contribute
to the rich biodiversity on the shores.
Status and threats: It is listed
as 'Vulnerable' on the Red List of threatened plants of Singapore.
of Spoon seagrass.
Chek Jawa, Jun 09
Sentosa, Jan 06
Changi, Apr 05
Tiny algae grow on the leaves which are eaten by tiny animals
Changi, May 05
Labrador, Nov 12
female flower of the spoon seagrass?
Changi, Apr 05
Chek Jawa, Jan 09
Photo shared by Loh Kok Sheng on his
Pulau Sekudu, Jun 06
Chek Jawa, Sep 11
Labrador, Nov 12
Labrador, Nov 12
seagrass on Singapore shores
Pulau Pawai, Dec 09
Pulau Biola, Dec 09
Pulau Salu, Aug 10
Pulau Berkas, May 10
Pulau Senang, Aug 10
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