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worms > Phylum Annelida > Class Polychaeta
Reef bristleworms
Eurythoe complanata*
Family Amphinomidae
updated Oct 2019

Where seen? This large active bristleworm is often encountered on many of our shores. On coral rubble near living reefs and seagrasses. It is especially active at night, foraging busily among the rubble. During the day, the worms are often hidden under stones.

What is a bristleworm? It is a segmented worm belonging to the Class Polychaeta, Phylum Annelida. The polychaetes include bristleworms, and Phylum Annelida includes the more familiar earthworm. Many members of the Family Amphinomidae are known as fireworms because of the burning pain they produce when handled.

Features: About 10-20cm long. Body flat, broad, tapered at both ends. Along the body are two rows of 'bunches' of bristles; long transparent bristles on the upperside, and a row of shorter bristles along the underside.
For each pair of bristle 'bunch' there is a short tuft. Colours greenish or pinkish, sometimes the tufts are red.

According to Leslie Harris, these worms belong to Family Amphinomidae, and appear to be Eurythoe complanata. There is some debate over whether this is one widespread species or a complex of species that look similar.

Fiery worms! The bristles are sharp easily penetrating bare skin. The bristles are filled with toxins. When irritated, the bristles are erected and break off easily, releasing the toxic contents into the wound. These cause a burning sensation, intense itching, inflammation and numbness that can last for days and even weeks.

How to stay safe: Wear covered shoes and long pants to cover all skin exposed to water. Do not touch bristleworms.
What do they eat? They feed on coral polyps, sponges, anemones, hydroids and ascidians. They lack jaws but suck out the juices of their prey.

Sentosa, Jul 05

Front of the worm.

Rows of bristle 'bunches'
with tufts.

Labrador, Mar 05

Tentative identification. Species are difficult to positively identify without close examination.
On this website, they are grouped by external features for convenience of display.

Reef bristleworms on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores

Punggol, Jun 12
Photo shared by Marcus Ng on flickr.

Pulau Sekudu, Oct 11
Photo shared by Loh Kok Sheng on his blog.

Sentosa Serapong, Dec 20
Photo shared by Vincent Choo on facebook.

Lazarus Island, Feb 11
Photo shared by James Koh on his blog

Hairy crab eating a Reef bristleworm.
Cyrene Reef, Oct 08
Photo shared by Toh Chay Hoon on flickr.

Pulau Semakau, Nov 09
Photo shared by Geraldine Lee on her blog.

Pulau Semakau South, Feb 16
Photo shared by Jianlin Liu on facebook.

Terumbu Pempang Tengah, Nov 18
Photo shared by Gina Tan on facebook.

Terumbu Raya, Mar 09
Photo shared by Loh Kok Sheng on his flickr.

With grateful thanks to Leslie H. Harris of the Natural History Museum of Los Angeles County for comments on this worm and a tentative identification.



  • Humann, Paul and Ned Deloach. 2010. Reef Creature Identification: Tropical Pacific New World Publications. 497pp.
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