| |
 Worms
that create tubes and live inside them are called tubeworms. The sand
bar, sandflats and mudflats of Chek Jawa are riddled with tubeworms
of all sizes, from thin delicate ones that look more like roots of
plants, translucent ones that look like drinking straws to ones as
thick as rubber tubing.
Tube-dwellers: Most tubeworms
are segmented bristleworms (Phylum Annelida,
Class Polychaeta). Some of these bristleworms have little hooks on
their sides to help them move up and down their tubes. Others have
reduced or no bristles. They are often beautifully iridescent. Some
have tentacles on their heads to filter feed at high tide or to sweep
the surroundings for edible titbits. Others have powerful jaws that
can give a nasty bite. They are ferocious predators that seize passing
prey while most of their bodies remain safely inside their tubes.
Tubes are so cosy that other creatures may move in with
the worm! Such creatures include tiny crabs, clams and other worms.
Made of worm snot! Most tubes are made with mucus. To strengthen
their tubes, some worms mix mucus with sand, shells or other debris.
Some tubes are slender, translucent straws. Others are as thick-walled
as rubber hoses and encrusted with all kinds of bits and pieces. Some
like the Solitary tubeworm (Diopatra sp.) may incorporate a
leaf at the top of the tube. This may help to reduce water loss or
transmit the vibrations of nearby predators or prey.
Why
live in a tube? A tube provides some protection from the
abrasive sand, as well as most predators. It is also a lair from which
predatory worms can hide to catch passing prey. Tubes may go quite
deep to where it remains moist and cool at low tide. Tubes that project
some distance above the bottom may allow the worms to reach clean,
oxygenated water above a muddy or sandy bottom. Building a tube on
a hard surface also allows worms to live in places where they cannot
burrow (see Keelworms).
Tubeworm babies: Most tubeworms
have separate genders. In some, eggs and sperm are released into the
water simultaneously where they are fertilised. In others, eggs are
retained or brooded within their tubes. Some eggs develop into free-swimming
larvae that drift with the plankton before settling down and developing
into new tubeworms.
Role in the ecosystem: Tubeworms
are eaten by many animals higher up in the food chain. Shorebirds,
for example, depend on worms, including tubeworms, for sustenance
to make their long migratory journeys.
The tubes of these worms may also help anchor sediments. In fact,
some tubeworms may live packed so closely together that they form
mounds up to 1m or more across! You can easily see some of these mounds
on Chek Jawa.
Human uses: Fishermen sometimes
dig out tubeworms to use as bait.
|
|
A variety of tubes
Thick tube with leaves
Diopatra sp.
A mound of
tubeworms
What do the worms
look like?
Here are some caught peeping out of their
tubes
|
See
also...
Worms of Chek Jawa.
Links
A Guide
To Singapore Polychaetes by Lim Yun Ping, the National University of
Singapore on the Acoustic Research Laboratory website: fact sheets and photos
of tubeworms found in Singapore.
Worms
on Life on
Australian Seashores by Keith Davey on the Marine Education Society
of Australia website: an introduction to worms (annelids, sipunculids) with
explanations of the major parts of their bodies and their lifestyles. Check
out the animation of a predatory
annelid worm catching its prey.
Marine Sedentary
Polychaetes in Hong Kong on the City University of Hong Kong website:
about polychaetes and tubeworms, with fact sheets and photos on lots of
species.
Other references
- Barnes, Robert
D. & Ruppert, Edward E., 1996. Invertebrate Zoology. Harcourt
College Publishers. 6th Edition. pp. 1056, G-1-16, I-1-30.
- Pechenik, Jan
A., 2000. Biology of the Invertebrates. McGraw-Hill Book Co.,
Singapore. 578 pp.
- Tan, Leo W. H.
& Ng, Peter K. L., 1988. A Guide to Seashore Life. The Singapore
Science Centre, Singapore. 160 pp. online
version
- Ng, Peter K. L.
& N. Sivasothi, 1999. A Guide to the Mangroves of Singapore II (Animal
Diversity). Singapore Science Centre. 168 pp.
|
