learn only 3 things about them ...
| Some species of ark clams have tiny hairs on the shell.
Their bodies are red because they have haemoglobin just
clams can cause cholera, hepatitis A and food poisoning.
seen? Among our favourite seafood, ark clams are still
seen on some undisturbed Northern shores. In Singapore, they are also
called 'see-ham'. On some shores, some species can still be found
in large groups. Usually on muddy shores where freshwater streams
reach the sea.
What are ark clams? Ark clams
belong to Family Arcidae. There are 200 species of ark clams, many
of them eaten extensively by people everywhere.
Features: 3-5cm. The two-part
shell is sturdy and often squarish. Some species have clear ribs,
others may be smooth. Members of this family of clams have a straight
hinge with many equal-sized teeth, called the taxodont hinge. Some
species of ark clams have shells covered in little brown hairs (called
the periostracum). Some species burrow in the mud or sand or simply
lie on the surface in heaps. Others live alone attached under stones.
Some species produce byssus threads to attach themselves to hard surfaces.
Unlike most other bivalves, some ark clam species have bodies that
are orange or reddish. This is due to the presence of haemoglobin,
the same substance that colours our own blood red too. Haemoglobin
assists in transporting oxygen within the body and help ark clams
thrive in oxygen-poor habitats.
What do they eat? Like most other
bivalves, ark clams are filter feeders. At high tide, they open their
shells a little. They then generate a current of water through the
shell and sieve out the food particles with enlarged gills. When the
tide goes out, they clamp up their shells tightly with a strong muscle
to prevent water loss.
Human uses: Ark clams are relished
in many local favourites such as fried kway teow and laksa. However,
ark clams may be affected by red
tide and other harmful algal blooms. They are also linked to cholera,
hepatitis A and dysenteric shellfish poisoning. Ark clams are farmed
in some places for sale as seafood.
Status and threats: None of our
ark clams are listed among the threatened animals of Singapore. However,
like other creatures of the intertidal zone, they are affected by
human activities such as reclamation and pollution. Trampling by careless
visitors and over-collection can also affect local populations of
|Some Ark clams on Singapore shores
Arcidae recorded for Singapore
Tan Siong Kiat and Henrietta P. M. Woo, 2010 Preliminary Checklist
of The Molluscs of Singapore.
+from The Biodiversity of Singapore, Lee Kong Chian Natural History Museum.
Anadara granosa=^Tegillarca granosa (See-ham or Blood cockle)
Arca avellana=^Arca patriarchalis
Barbatia sp. (Barbatia ark
Barbatia tenella=^Calloarca tenella
Scapharca gubernaculum=^Anadara gubernaculum
- Tan Siong
Kiat and Henrietta P. M. Woo, 2010 Preliminary
Checklist of The Molluscs of Singapore (pdf), Raffles
Museum of Biodiversity Research, National University of Singapore.
- Tan, K. S.
& L. M. Chou, 2000. A
Guide to the Common Seashells of Singapore. Singapore
Science Centre. 160 pp.
- Wee Y.C.
and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore.
National Council on the Environment. 163pp.
- Ng, P. K.
L. & Y. C. Wee, 1994. The
Singapore Red Data Book: Threatened Plants and Animals of Singapore.
The Nature Society (Singapore), Singapore. 343 pp.
- Abbott, R.
Tucker, 1991. Seashells
of South East Asia.
Graham Brash, Singapore. 145 pp.