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worms > Phylum Platyhelminthes > Class Turbellaria > Order Polycladida
Orsak's flatworm
Nymphozoon orsaki
Family Pseudocerotidae
updated Feb 2020

Where seen? This flatworm is sometimes seen on coral rubble near living reefs.

Features: 5-6cm long. Body background pinkish cream. Narrow black margin with inner orange margin. Along the middle of the body, one fine white stripe. The underside is same colour as upper body colour and margins. It has a pair of pseudotentacles that are squarish and ruffled on the sides, with white tips.

Sometimes mistaken for the Brown-striped flatworm which is more brown and has a broad dark stripe in the middle of the body.

Pseudotentacles squarish, ruffled on the sides, with white tips.

Lazarus Island, Nov 14
Photo shared by Loh Kok Sheng on flickr.

Terumbu Bemban, Jul 18
Photo shared by Abel Yeo on facebook..

Pulau Jong, Aug 21
Photo shared by Vincent Choo on facebook.

Pulau Jong, Jan 23
Photo shared by Che Cheng New on facebook.

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


  • 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.
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