you learn only 3 things about them ...
Sponges are animals and not plants! Don't break them or
step on them.
Many small animals live inside sponges. Look for them.
can cause skin irritation. Don't handle sponges!
Sponges are commonly seen on almost all our shores. They grow on all
kinds of hard surfaces, from boulders, jetty pilings to coral rubble
and even other animals. While many are large and colourful, others
may be small, found under stones and other hiding places and thus
What are sponges? Often mistaken for plants, sponges are
actually animals, albeit very simple animals. In fact, scientists
did not even consider animals until about 100 years ago! Sponges belong
to Phylum Porifera which includes about 8,000 known species.
Features: A sponge is a simple animal made up of a few
types of cells. These cells are largely independent of one another
and only loosely held together. These cells do not form tissues or
organs, so a sponge does not have a mouth, digestive system or circulatory
system. A sponge is NOT a colony, in the way that a hard coral is
a colony of individual animals.
Sometimes mistaken for other blob-like animals such as
and even seaweed. Here's more on how to tell apart blob-like
Riddled with canals: Sponges have a unique body plan based
on a system of fine, branching canals. The sponge generates a flow
of water through these canals and traps microscopic particles from
this water flow
Here's how it works: Inside the sponge, tiny branching canals
lead to chambers. Lining these chambers are cells, each with a single
beating hair. The beating of these hairs generates a current through
the sponge. Water is sucked in through tiny holes on the surface of
the sponge. 'Porifera' means 'pore-bearing'.
These tiny holes lead to the branching canals. As the canals narrow,
microscopic organic particles, bacteria and plankton in the water
are captured and engulfed by the cells of the sponge. Oxygen is also
absorbed. The water is then expelled out of larger holes, together
with any wastes.
In this way, a sponge can filter water many times its body volume
in a short time. In general, a sponge can pump water equal to its
body volume once every 5 seconds!
A sponge constantly remoulds and finetunes its structure to ensure
efficient filter feeding. A sponge can control the flow of water through
it, and even stop it altogether (e.g., when the water is too silty).
Sponging sponges: Some sponges
harbour symbiotic organisms in their bodies. These organisms undergo
photosynthesis to produce food from sunlight. The food produced is
shared with the host, which in return provides the symbionts with
shelter and minerals. Sponge symbionts include zooxanthallae as well
A single sponge may harbour several different kinds of symbionts!
Sponges Not Softies: Although they look soft and are generally
immobile, sponges are not as defenceless as they appear.
Many sponges have a skeleton made up of tough, elastic fibres made
of a protein called spongin. Sponges may also have a framework of
spicules (tiny, hard spikes) throughout their body. Spicules may be
made up of calcium carbonate (like our bones) or silica (the same
substance that glass is made of). These spicules are often sharp and
needle-like. Inside the body, spicules provide support, keeping the
sponge upright and their canals open. Spicules also makes them an
unpleasant mouthful. Spicules may also stick out of the surface, giving
the sponge a rough texture.
Some sponges have a spongin-only framework. Those with dense spongin
skeletons feel firm, tough and rubbery. But most sponges have both
spongin and spicules and feel rough to the touch.
rash: Some sponges
release chemicals which irritate and deter other creatures
(including other sponges) from growing over them. Others
produce toxins or foul-tasting chemicals to deter sponge-eaters.
In fact, some sponges might give you a rash. So avoid
How to stay safe:
Don't touch sponges.
Strange sponge shapes: Sponges
may grow as a thin encrusting layer under and over hard surfaces.
Others may grow upright in branches or in the shape of balls, tubes,
vases or spikes. A sponge of one species may grow in different shapes
depending on its environment. It may form into a thinner mat in places
with strong currents, and into thicker masses in calmer waters. Sponges
are only positively identified by their spicules (tiny hard spikes)
that riddle their bodies.
Why so colourful? Scientists don't
really know why. One suggestion is that the vivid colours of some
sponges warn of their toxic or distasteful nature. The colours might
also be a kind of sunblock that protect from harmful rays of the sun.
Some sponges harbour symbiotic algae that may colour them green, violet
Sponge babies: Sponges have amazing
regenerative powers. Not only can they repair damage to their bodies,
but a whole sponge can slowly grow from a small bit that broke off.
But this takes time, so please don't break the sponges on purpose.
Sponges, however, do reproduce sexually. Most sponges are hermaphrodites,
being able to perform both male and female functions. But usually,
a sponge will play one role at a time. Some cells of the sponge change
into eggs or sperm. While eggs are generally retained, sperm are released
into the water. When sperm are 'inhaled' by another sponge of the
same species, these fertilise the eggs. The eggs develop within the
parent sponge. The free-swimming larvae leave the parent sponge and
settle down to become new sponges.
Role in the habitat: With its natural defences and a constant
flow of water through it, a sponge is a safe, well-oxygenated home
for tiny creatures. A large sponge may be home to a vast number and
variety of such tiny animals that live in the labyrinth of canals
and chambers inside the sponge. These include crabs, brittle
stars and tiny snapping
Besides finding shelter, some creatures may eat larger particles that
accumulate on the sponge surface. It is said that some may even feed
on substances produced by the sponge. These include synaptid
Larger animals may also exploit sponges for protection. For example,
the Velcro crab
and Sponge crab
use sponges for camouflage. Sponges are also eaten by animals, such
as nudibranchs, that have
adapted to deal with sponge defences. Although most sponges are toxic
to fish, some fishes specialise in eating sponges. Sea turtles also
Human uses: Today, the sponges
you use at home are synthetic and not made from living sponges. In
the past, natural sponges were used for padding and packing, to paint
with and to bathe with. Natural sponges are still used today as luxury
bath items. These are made from sponges that only produce spongin
skeletons and do not have lots of sharp, poky spicules like most other
sponges: most commercial bath sponges are made from Spongia officinalis
of the Family Spongiidae that is found in the Mediterranean Sea. While
sponges in the Family Spongiidae can be
found in Singapore, you certainly should not even touch most of our
sponges as they have spicules that can cause skin irritation, much
less bathe with them!
Nowadays, living sponges have become important as potential sources
of new medicines. The toxins and foul-tasting substances that sponges
have developed to defend themselves are being studied for medical
applications such as new antibiotics.
Status and threats: None of our
sponges 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
sponges. Please don't break the sponges. They take time to regrow
and are homes to other animals. Some sponges may also cause skin irritation.
Grateful thanks to Lim Swee Cheng for identifying some
of the sponges on this site.
- Low MEY (2012) The date of publication of Cliona patera (Hardwicke), the ‘sponge plant from the shores of Singapore’ (Porifera: Hadromerida: Clionaidae). Nature in Singapore, 5: 223–227.
Lim; Nicole J. de Voogd; Koh-Siang Tan: Biodiversity
of shallow-water sponges (Porifera) in Singapore and description
of a new species of Forcepia (Poecilosclerida: Coelosphaeridae) (pdf) Contributions to Zoology, 81 (1) 55-71 (2012)
Lim, Nicole J. de Voogd and Koh-Siang Tan. Fouling
sponges (Porifera) on navigation buoys from Singapore waters. The Raffles Bulletin of Zoology Supplement No.
22: 41-68, 30 Dec 2009 Pp. 41-58.
- Lim Swee
Cheng, Nicole de Voogd and Tan Koh Siang. 2008. A
Guide to Sponges of Singapore. Singapore Science Centre.
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Sea Challengers. 314pp.
- Allen, Gerald
R and Roger Steene. 2002. Indo-Pacific
Coral Reef Field Guide.
Tropical Reef Research. 378pp.
- 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.
- 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,
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