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Phylum Mollusca > Class Gastropoda > sea slugs > Order Nudibranchia
'Jolly Green Giant' nudibranch
Miamira sinuatum
Family Chromodorididae
updated May 2020
Where seen? This large chunky hard nudibranch is sometimes seen among coral rubble and reefs on our Southern islands. Usually several are seen at the same time, and then none for a while. It does look rather jolly and is large! It was previously known as Ceratosoma sinuatum.

Features: 6-8cm long. The body is stiff, narrow with a short, broad tail. The front of the body generally pointed. The body edge has regular undulating lobes along the edge of the mantle from front to end. The lobes are armed with glands that secrete distasteful substances to discourage predators. There is a large horn-like lobe in front of the feathery gills. Colours usually green, with small yellow bumps, sometimes with tiny blue spots. The gills have tiny yellow spots.

Like other members of the Family Chromodorididae, the Ceratosoma nudibranch absorbs the toxic chemicals in their sponge food and incorporate these chemicals into the mantle glands. According to Bill Rudman, most species of Ceratosoma have a long 'horn' that stick out and curves towards the head. This acts as a defensive lure attracting and sacrificed to potential predators. This 'horn' contains most of the distasteful chemicals stored from the sponges that they feed on.

What does it eat? It is eats sponges.

Large lobe in front of gills.
Pulau Semakau, Sep 05

Sisters Island, Jul 06

Small rhinophores.

Pulau Semakau, Feb 09

Feathery gills with yellow spots.
Labrador, Mar 07

Terumbu Semakau, May 10

'Jolly Green Giant' nudibranchs on Singapore shores
On wildsingapore flickr

Other sightings on Singapore shores

Releasing white fluid when alarmed.
Pulau Hantu, Aug 15
Photo shared by Marcus Ng on flickr.

Tanah Merah, Jul 09
Photo shared by James Koh on flickr.

Pulau Hantu, Aug 15
Photo shared by Marcus Ng on facebook.



  • Tan Siong Kiat and Henrietta P. M. Woo, 2010 Preliminary Checklist of The Molluscs of Singapore (pdf), Raffles Museum of Biodiversity Research, National University of Singapore.
  • Debelius, Helmut, 2001. Nudibranchs and Sea Snails: Indo-Pacific Field Guide IKAN-Unterwasserachiv, Frankfurt. 321 pp.
  • Wells, Fred E. and Clayton W. Bryce. 2000. Slugs of Western Australia: A guide to the species from the Indian to West Pacific Oceans. Western Australian Museum. 184 pp.
  • Coleman, Neville. 2001. 1001 Nudibranchs: Catalogue of Indo-Pacific Sea Slugs. Neville Coleman's Underwater Geographic Pty Ltd, Australia.144pp.
  • Coleman, Neville, 1989. Nudibranchs of the South Pacific Vol 1. 64 pp.
  • Humann, Paul and Ned Deloach. 2010. Reef Creature Identification:Tropical Pacific New World Publications. 497pp.
  • 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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