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worms > Phylum Platyhelminthes > Class Turbellaria > Order Polycladida
Racing-line flatworm
Pseudoceros bifurcus
Family Pseudocerotidae
updated Feb 2020

Where seen? Like a blue race-car with a colourful line along the side, this stunning flatworm is sometimes seen on coral rubble near living reefs.

Features: 4-5cm long. Body solid blue to bluish purple (not bluish-white). The central line is white (not yellow or golden) becoming orange or red near the head, the line is edged with a thin dark purple border. It has a pair of pseudotentacles made up of simple folded edges of the body.

What does it eat? It eats colonial ascidians, possibly the pink ascidian. It may have a more generalised diet, preying on a variety of ascidians.

Sometimes mistaken for similar flatworms. Here's more on how to tell apart small flatworms with one central line and three central lines.

Tuas, Nov 03

Central line white becoming orange/red near the head, edged with dark purple border.

Racing-line flatworms on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores

Changi, Aug 19
Shared by Loh Kok Sheng on facebook.

Changi, Jul 12
Photo shared by Neo Mei Lin on her blog.

Changi, Aug 19
Photo shared by Jianlin Liu on facebook.

Chek Jawa, Dec 19
Photo shared by Loh Kok Sheng on facebook.

Pulau Sekudu, Jul 19
Photo shared by Jianlin Liu on facebook.

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

Sentosa Serapong, May 17*
Shared by Loh Kok Sheng on facebook.

Sentosa Serapong, May 17
Shared by Loh Kok Sheng on facebook.

Sentosa Serapong, May 16*
Photo shared by Marcus Ng on facebook.

Beting Bemban Besar, Mar 20
Shared by Vincent Choo on facebook.

Pulau Semakau, Feb 08
Shared by Lim Swee Cheng on his flickr.

Grateful thanks to Rene Ong for sharing details and identifying the flatworms on this page.


  • Pseudoceros bifurcus on Encyclopedia of Life, LifeDesks, Marine Flatworms - Polycladida: Technical fact sheet.


  • Rene S.L. Ong and Samantha J.W. Tong. 29 October 2018. A preliminary checklist and photographic catalogue of polyclad flatworms recorded from Singapore. Nature in Singapore 2018 11: 77–125
  • D. M. Bolaños, B. Q. Gan & R. S. L. Ong. 29 Jun 2016. First records of pseudocerotid flatworms (Platyhelminthes: Polycladida: Cotylea) from Singapore: A taxonomic report with remarks on colour variation.(pdf) The Raffles Bulletin of Zoology Supplement No. 34: 130-169  Pp. 130-169.
  • Newman, L.J. & Cannon, L.R.G. Pseudoceros (Platyhelminthes: Polycladida) from the Indo-Pacific with twelve new species from Australia and Papua New Guinea. The Raffles Bulletin of Zoology 1998 Pp. 293-323.
  • Newman, Leslie and Lester Cannon. 2003. Marine Flatworms: The World of Polyclads. CSIRO Publishing. 97pp.
  • 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.
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