> Phylum Annelida > Class Polychaeta
learn only 3 things about them ...
bristles can cause severe pain. Don't touch!
They have well developed heads with specialised jaws.
have a spectacular way of reproducing.
seen? Bristleworms are abundant on our shores. Even the most 'beat up' shore
will have these worms. But they are rarely seen as they burrow in
the ground or remain in other hiding places. In coral rubble, giant
reef worms that grow to 1m long hide inside crevices. Others about
10cm long crawl about in sandy and muddy areas. Some beautiful ones
swim about in the water. Others live in tubes.
Countless microscopic ones too small to see live among the sand grains.
What are bristleworms? Bristleworms
are segmented worms belonging to Phylum
Annelida like the more familiar earthworm. There are about 8,000 species
of polychaete worms, making them the largest class of the segmented
Features: These worms have bodies
that are divided into segments. Except for the head and last segment,
all the segments are generally similar. Each segment has a pair of
flattened extensions called parapodia. These appendages are usually
branched at the ends and covered with bristles, called setae. 'Polychaeta'
means 'many bristles'. And indeed, they have lots of bristles.
These bristly appendages are sometimes used to move (much like a centipede
does) and to burrow. In tubeworms,
the appendages help grip the tube walls and to move up and down the
tubes. In some large active bristleworms that need more oxygen, the parapodia
function as gills.
Sometimes confused with brittlestars.
Here's more on how to tell them
Pulau Sekudu, Aug 04
Bristles on the sides of the worm
This tiny tubeworm has eyes,
and feathery appendages on the
sides that act as gills.
Changi, Jul 04
|Complex worms: Bristleworms are
rather complex and well developed. Most have a well-developed blood
circulatory system. Their heads bear eyes (from 2 to 4 pairs), sensory
organs, the mouth and contain a brain. Many have specialised feeding
structures on their head. These can range from powerful jaws to long
tentacles that collect food.
Bristleworms have amazing powers of regeneration. Many can replace
body parts that get chomped off by predators. This even includes the
Mobile versus immobile: The various
kinds of bristleworms are often grouped into those that are free-moving
(called errant polychaetes) and those that are not (called sedentary
polychaetes). These sedentary worms usually live
in tubes or burrows. However, the distinction is not always clear.
There are errant polychaetes that live in tubes or don't move about
much and hide in burrows or other places.
Beautiful worms: Large, freely-moving
bristleworms can be attractive, with iridescent colours in shades
of red, pink and green. Among the most beautiful of bristleworms is
the fan worm (Family Sabellidae) with
a delicate, patterned feathery fan of feeding tentacles.
Monster worm: While bristleworms
we commonly see grow to about 10cm long, the Giant
reef worm can grow to more than 1m long!
play with fire! Fireworms have bristles made of calcium carbonate or silica which
are brittle and contain poisons. The hairy bristles are
sharp and can easily penetrate bare skin. The bristles
are brittle and break off easily inside the skin. The
embedded bristles cause a burning sensation, intense itching,
inflammation and numbness that can last for days and even
weeks. These creatures are not surprisingly called fireworms.
Fireworms may release their bristles into the water too.
Don't touch bristleworms or the water that they are in!
How to stay safe: Wear covered shoes and long pants to cover all skin exposed
to water. Do not touch bristleworms.
This fireworm swims actively
and has really elaborate bristles.
Raffles Marina, Apr 05
Fanworms are bristleworms with a delicate fan of feathery tentacles on their heads.
Pulau Hantu, Aug 04
Scale worms are tiny and often overlooked.
Terumbu Pempang Laut, May 12
|What do they eat? Some bristleworms
are ferocious predators, hunting other worms and small animals. These
are captured with strong jaws that can be extended and retracted.
Some can inject a poison with their jaws. Some predatory bristleworms
live in tubes where they lie in wait for suitable prey.
Other bristleworms feed harmlessly on algae, others are scavengers.
Yet others feed on detritus. They may swallow sand and mud and process
these for the edible bits, others have tentacles and other appendages
on their heads to sweep the surface for detritus or collect detritus
suspended in the water. The fanworm has feathery tentacles to filter
food from the water.
Worm babies: While some bristleworms
can reproduce asexually by budding or dividing their bodies into parts,
most bristleworms reproduce sexually. Most bristleworms have separate
genders. In some, eggs and sperm are released into the water simultaneously
where they are fertilised. In many, the eggs develop into free-swimming
larvae that drift with the plankton before settling down and developing
into new bristleworms.
Ripping apart to reproduce! Some
bristleworms reproduce by epitoky: a portion of the bristleworm becomes
packed with eggs or sperm and becomes highly specialised for swimming,
some even developing eyes! This portion is called the epitoke. At
mating time, the epitoke breaks off from the main worm and can move
about on its own. Swimming to the surface, it is joined by the epitokes
of other bristleworms. At the surface, the epitokes burst apart, releasing
eggs and sperm for external fertilisation. In this way, the worms
can reproduce without exposing the rest of their bodies to danger.
However, while an epitoke might be a new segment produced by the animal,
sometimes the entire animal is remodelled into an epitoke and rips
itself apart during mating. Mating is usually triggered by the lunar
The Singapore Biodiversity Records has an article that might be related to bristleworm reproduction: "Hundreds of mud-worms, mostly metallic blue but some pale red, each around 20 to 30 cm long, were observed swimming about in the water (see accompanying picture), and appeared to be gradually growing in numbers. Very little is known about the life cycle of this large worm. It is suspected that the swarming phenomenon ties in with their reproductive strategy, where sexually mature worms swim to the water surface in temporal and spatial synchrony to increase the chances of successful fertilisation of their eggs."
Role in the ecosystem: Bristleworms are eaten by many
creatures higher up in the food chain. Shorebirds, for example, depend
on worms for sustenance to make their long migrations.
Human uses: Fishermen sometimes
dig out bristleworms to use as bait.
Status and threats: 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 have an impact on local populations.
Polychaeta recorded for Singapore (some
Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity
in red are those listed among the threatened
animals of Singapore from Davison, G.W. H. and P. K. L. Ng
and Ho Hua Chew, 2008. The Singapore Red Data Book: Threatened
plants and animals of Singapore.
*from A Guide to Singapore
Polychaetes by Lim Yun Ping 1997-2000.
seen awaiting identification
Species are difficult to positively identify without
On this website, they are grouped by external features for convenience
Chaetopterus variopedatus (EN:
Eunice aphroditois (Giant reef
Eunice lucei=**Leodice lucei
||Diopatra sp. (Solitary tube worm)
*Diopatra bulohensis=**Diopatra claparedii
|| Lepidonotus sp.
Terebellidae (terebellid worms)
With grateful thanks to Leslie H. Harris of the Natural
History Museum of Los Angeles County for comments on and
identifying some of these bristleworms.
Worms (Phylum Annelida) Tan, Leo W. H. & Ng, Peter K.
L., 1988. A
Guide to Seashore Life. The Singapore Science Centre,
Singapore. 160 pp.
Worms (Annelids) Ng, Peter K. L. & N. Sivasothi, 1999. A Guide
to the Mangroves of Singapore II (Animal Diversity).
Singapore Science Centre. 168 pp.
Guide to Singapore Polychaetes by Lim Yun Ping 1997-2000
on the Raffles Museum of Biodiversity Research website:
fact sheets and photos of polychaetes 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.
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.
Errant Polychaetes in Hong Kong by P L Chan, 2000 on
the City University of Hong Kong website: introduction to
polychaetes, description and photos of major families, identification
key, glossary, references and links.
and their larvae by by Wim van Egmond on the Microscopy
UK website: lots of lovely super close look at the fascinating
larvae of bristleworms.
- Lee Yen-ling & Morgany Thangavelu. 31 Mar 2017. Metallic blue and red mud-worms at Pasir Ris mangrove. Singapore Biodiversity Records 2017:42-43.
Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity
in Singapore. National Council on the Environment. 163pp.
G.W. H. and P. K. L. Ng and Ho Hua Chew, 2008. The Singapore
Red Data Book: Threatened plants and animals of Singapore.
Nature Society (Singapore). 285 pp.
Terrence M., David W. Behrens and Gary C. Williams. 1996. Coral
Reef Animals of the Indo-Pacific: Animal life from Africa
to Hawaii exclusive of the vertebrates Sea Challengers. 314pp.
Gerald R and Roger Steene. 2002. Indo-Pacific
Coral Reef Field Guide.
Tropical Reef Research. 378pp.
E. Ruppert, Richard S. Fox, Robert D. Barnes. 2004.Invertebrate
Zoology Brooks/Cole of Thomson Learning Inc., 7th Edition. pp. 963
Jan A., 2005. Biology
of the Invertebrates.
5th edition. McGraw-Hill Book Co., Singapore.
R.E. (Ed.) et al. 2000. Polychaetes and Allies: The Southern
Synthesis Australian Biological Resources Study, Canberra.