| |
Some small clumps of living soft corals may be seen at the coral rubble
area. When exposed at low tide, they often flop over and look like
a pile of jelly. When submerged, however, they expand into beautiful
plant-like forms.
Living fogether: Soft corals belong
to the same group as sea anemones. While sea anemones are large solitary
polyps, soft corals are colonies of tiny, individual polyps linked
to each other. Soft corals can look like branching bushes or trees.
They may also be flatter and look like mushrooms.
Soft support: Unlike hard corals,
soft corals don't produce a hard skeleton. Instead the polyps are
connected by a soft tissue mass. Tiny spikes of calcium carbonate,
called sclerites, are embedded in the tissue mass. These sclerites
are used to identify soft coral species. In some, the sclerites are
far apart resulting in a more floppy soft coral. In others, the sclerites
are closer or fused together to form firmer support. The entire tissue
mass is covered with a skin and the polyp tentacles emerge through
this skin. In some soft corals, the skin can be quite tough and leathery
looking, and these are called leather corals. Out of water, soft corals
may flop over and may look small. But underwater, they expand and
spread out to filter the water for food.
Colonial food: Most soft corals
feed on plankton, some also feed on finer particles. Like other cnidarians,
soft coral polyps have tentacles with stingers to capture food. Unlike
hard corals which have only six tentacles, soft coral polyps have
eight tentacles. Soft coral tentacles are also pinnate (branched or
feathery). Many harbour zooxanthellae (symbiotic single-celled algae)
inside their bodies. These carry out photosynthesis and contribute
nutrients to the host polyp.
Coral babies: Soft corals can
reproduce asexually: budding of new polyps enlarges the colony. However,
they also reproduce sexually. The polyps may produce sperm or eggs.
The eggs develop into free-swimming larvae that drift with the plankton
before settling down to start a new colonies.
Human uses: Soft corals protect
themselves with unusual substances which are being studied for possible
anti-cancer properties. Soft corals are also harvested from the wild
for the aquarium trade. Living coral reefs, however, are worth far
more to humans when they left alone. Reefs bring in tourists which
generate business beyond the shore (e.g., hotels, restaurants and
travel-related industries).
Status and threats: Like other
creatures of the sea, soft corals are threatened by human activities
that degrade or destroy the habitat. |
|
A close up of the individual polyps
Under water,
soft coral look
like plants |
See
also ...
Cnidarians in general
Links
Soft
corals on the CRC Reef Research Centre website: brief introduction to
soft corals and links to more articles.
Farming
Soft Corals for the Marine Aquarium Trade by Simon Ellis on the University
of Hawaii Kapiolani Community College Library website: about farming soft
corals with some information about the biology of soft corals and photos
of commercially important soft corals.
Soft
corals shrug off poor image on the CRC Reef Centre website: preliminary
findings of a study on the role of soft corals in offshore and inshore reefs,
and some info on their applications in human medicine.
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
- Davey, Keith,
1998. A Photographic Guide to Seashore Life of Australia. New
Holland, Australia.144 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.
|
