learn only 3 things about them ...
They are animals! Although they look like plants.
They don't produce a hard skeleton.
soft coral is a colony of countless tiny polyps.
seen? Soft corals are commonly seen on many of our shores.
Some resemble flowery bushes, others giant leathery disks. Yet others
are tiny and overlooked. They are found growing on boulders and other
hard surfaces, as well as among coral rubble and living hard corals
on the reef flats.
What are soft corals? Soft corals
belong to Phylum Cnidaria which includes
the more familiar sea anemones, hard corals and jellyfishes. Soft
corals are members of the Subclass Alcyonaria/ Octocorallia that includes
gorgonians and sea
Within this Subclass, the Order Alcyonacea includes flowery
soft corals (Family Nephtheidae) as well as leathery
soft corals (Family Alcyoniidae).
Features: Soft corals are colonies
of tiny, individual polyps linked to one another. Soft corals can
look like branching bushes or trees. They may also be flatter and
look like mushrooms. When exposed at low tide, they often flop over
and look like a pile of jelly or fried eggs! When submerged, however,
they expand into beautiful plant-like forms and some appear 'furry'
as the tiny polyps expand.
Soft coral polyps have 8 (or multiple of 8) tentacles that are pinnate
(branched or feathery). Some soft corals like leathery
soft corals have two kinds of polyps: Autozooids have long stalks
with eight branched tentacles and emerge from the shared leathery
tissue. Siphonozooids may be much shorter polyps or don't even emerge
from the shared tissue and function as water pumps for the colony.
Sometimes mistaken for sea
anemones. Some large sea anemones and large leathery and flowery
soft corals may be mistaken for one another. Here's more on how
to tell apart large 'hairy' disk-like animals on the shore.
Soft support: Although there are
some exceptions, many soft corals don't produce a hard skeleton. Instead
in colonial soft corals, the polyps are connected by a shared tissue.
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, thus these are often
called leathery soft corals. Out of water, soft corals may flop over
and may look small. But underwater, they expand and spread out to
maximise the feeding surface.
What do they eat? 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.
Many soft corals harbour microscopic, single-celled symbiotic algae
(zooxanthellae) within their bodies. The algae undergo photosynthesis
to produce food from sunlight. The food produced is shared with the
host, which in return provides the algae with shelter and minerals.
Role in the habitat: Some soft
corals are homes to tiny animals. Some tiny animals eat soft corals
and look just like their much larger prey.
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
Status and threats: Like other
creatures of the sea, soft corals are threatened by human activities
that degrade or destroy the habitat. Trampling
by careless visitors, and over-collection also have an impact on local
corals on Singapore shores
Alcyonacea recorded for Singapore
Y. Benayahu and L. M. Chou, 28 Feb 2010. On some Octocorallia (Cnidaria:
Anthozoa: Alcyonacea) from Singapore
*Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in
Groups from Fabricius, Katharina and Philip Alderslade, 2001. Soft
Corals and Sea Fans.
+from our observation
are included in this group
Other 'soft coral' orders
Pennatulacea (sea pens)
- Y. Benayahu
and L. M. Chou, 28 Feb 2010. On
some Octocorallia (Cnidaria: Anthozoa: Alcyonacea) from Singapore,
with a description of a new Cladiella species. The Raffles
Bulletin of Zoology. Pp. 1-13.
Eric H. 2001. Aquarium
Corals: Selection, Husbandry and Natural History
T.F. H Publications. 464 pp
Katharina and Philip Alderslade, 2001. Soft
Corals and Sea Fans.
Australian Institute of Marine Science and the Museum and Art
Gallery of the Northern Territoriy. 264 pp
- Edward E.
Ruppert, Richard S. Fox, Robert D. Barnes. 2004.Invertebrate
Brooks/Cole of Thomson Learning Inc., 7th Edition. pp. 963
Jan A., 2005. Biology
of the Invertebrates.
5th edition. McGraw-Hill Book Co., Singapore. 578 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.