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worms > Phylum Annelida > Class Polychaeta
Class Polychaeta
updated Oct 2019

if you learn only 3 things about them ...
Their bristles can cause severe pain. Don't touch!
They have well developed heads with specialised jaws.
Some have a spectacular way of reproducing.

Where 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 worms.

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 apart.

Pulau Sekudu, Aug 04

Bristles on the sides of the worm

This tiny tubeworm has eyes, tentacles,
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 head!

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!

Don't 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 cycle.

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.

Class Polychaeta recorded for Singapore (some families)
from Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore.
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.
**from WORMS

  Bristleworms seen awaiting identification
Species are difficult to positively identify without close examination.
On this website, they are grouped by external features for convenience of display.
  Gregarious tubeworms
Many bristleworms live in tubes and are called tubeworms
Spaghetti worms

  Family Amphinomidae
  Chloeia sp. (Beautiful fireworm)
Chloeia capillata=**Chloeia flava
Chloeia flava

Eurythoe complanata
(Reef bristleworms)

  Family Capitellidae
  Capitella capitata


  Family Chaetopteridae (straw tubeworms)
  *Chaetopterus cariopedatus
Chaetopterus variopedatus
(EN: Endangered)

  Family Cirratulidae
  Cirratulus cirratulus

  Family Cirratulidae
  Cirratulus cirratulus

  Family Eunicidae
  Eunice antennata=**Leodice antennata
Eunice aphroditois (Giant reef worm)
Eunice coccinioides
Eunice grubei
Eunice hirschi
Eunice lucei=**Leodice lucei
Eunice nesiotes

Euniphysa aculeata

Lysidice collaris

Marphysa disjuncta
Marphysa macintoshi
Marphysa mossambica

  Family Hesionidae
  Oxydromus cf. angustifrons (Urchin-mouth worm)

  Family Onuiphidae
  Diopatra sp. (Solitary tube worm)
Diopatra neapolitana
*Diopatra bulohensis=**Diopatra claparedii

  Family Polynoidae (scale worms)
  Lepidonotus sp.

Paralepidonotus ampulliferus

  Family Sabellidae (fan worms) with list of species recorded for Singapore

  Family Serpulidae (keelworms)
  Spirobranchus sp.

  Family Spionidae
  Paraprionospio sp.


Prionospio komaeti
Prionospio malayensis

  Family Terebellidae (terebellid worms)
  Loimia medusa

Nicolea gracilibranchis

Thelepus gracilis
Thelepus setosus

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.



  • Lee Yen-ling & Morgany Thangavelu. 31 Mar 2017. Metallic blue and red mud-worms at Pasir Ris mangrove. Singapore Biodiversity Records 2017:42-43.
  • Wee Y.C. and Peter K. L. Ng. 1994. A First Look at Biodiversity in Singapore. National Council on the Environment. 163pp.
  • 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. Nature Society (Singapore). 285 pp.
  • Gosliner, 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.
  • 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 Zoology Brooks/Cole of Thomson Learning Inc., 7th Edition. pp. 963
  • Pechenik, Jan A., 2005. Biology of the Invertebrates. 5th edition. McGraw-Hill Book Co., Singapore. 578 pp.
  • Jones, R.E. (Ed.) et al. 2000. Polychaetes and Allies: The Southern Synthesis Australian Biological Resources Study, Canberra. 465pp.
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