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Cerianthid phoronid worm
Phoronis australis*
Phylum Phoronida
updated Oct 2019
if you learn only 3 things about them ...
They are often seen near cerianthids. They are shy and hide at the slightest sign of danger. Be quiet and wait for them to emerge.
They look like fanworms but belong to a different animal group.
Their tubes are made of chitin, the same substance that insect exoskeleton is made of.

Where seen? Literally overshadowed by their more glamorous hosts, this tiny fluffy worm is commonly seen with cerianthids on our northern shores. Often several can be seen near one cerianthid. Very shy, the worms retract at the slightest sign of danger. There's a better chance of seeing them at night.

What are phoronid worms? Phoronid worms are unsegmented worms belonging to Phylum Phoronida. This is a small phylum with less than 20 species. They build and live inside tubes made of chitin. Phoronis australis is thus far, the only phoronid known to be encountered with cerianthids and it is found in all warm temperate to tropical coasts from the intertidal to deeper waters.

Features: Phoronis australis has a pair of feathery spiralling tentacles (diameter about 2cm). The body is long, unsegemented and worm-like. Those seen on our shores are grey or pinkish black, but elsewhere white ones are also seen. Most phoronids build a tube that is made of chitin (the same substance that insect skeletons are made of). More about tubeworms in general.

Sometimes confused with
fan worms. Fan worms are segmented worms belonging to Phylum Annelida, Class Polychaeta. More on how to tell apart animals with a ring of feathery tentacles.

According to Gosliner, the body of Phoronis australis penetrates the tissues of the cerianthid but the phoronid worm is not parasitic and does not absorb nutrients from the cerianthid directly.

What do they eat? Phoronids are filter feeders, creating a current of water through their spiral of tentatcles. Edible bits are trapped in mucus on the tentacles.

Phoronid babies: Some phoronids can reproduce by budding or splitting into half. They also reproduce by producing eggs and sperm. It is believed that the lifespan of phoronids is only about one year. Phoronis australis is a hermaphrodite.

Phoroneus the hero: In Greek mythology, Phoroneus is often said to be the son of a river god and ocean nymph. He is credited for being the first to unite the Greeks as one people. Previously, they had lived in scattered groups.

Changi, Jun 03

Are the white stuff eggs?
Changi, Aug 05

The anus is at the top of the body
in between the two 'fans'.
Changi, Aug 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.

Cerianthid phoronid worms on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores

Tuas, Mar 15
Photo shared by Marcus Ng on facebook.

Pulau Ubin, Jul 17
Photo shared by Loh Kok Sheng on facebook.

Pulau Semakau, Sep 09
Photo shared by Loh Kok Sheng on flickr.

Pulau Sudong, Dec 09
Photo shared by Toh Chay Hoon on flickr.

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



  • 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.
  • Morton, Brian & John Morton, 1983. The Sea Shore Ecology of Hong Kong. Hong Kong University Press. 350 pp.
  • Allen, Gerald R and Roger Steene. 2002. Indo-Pacific Coral Reef Field Guide. Tropical Reef Research. 378pp.
  • Humann, Paul and Ned Deloach. 2010. Reef Creature Identification: Tropical Pacific New World Publications. 497pp.
  • Kuiter, Rudie H and Helmut Debelius. 2009. World Atlas of Marine Fauna. IKAN-Unterwasserachiv. 723pp.
  • 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.
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