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Phylum Mollusca > Class Gastropoda > sea slugs > Order Nudibranchia
Blue-spot nudibranch
Dendrodoris denisoni
Family Dendrodorididae
updated Oct 2016
Where seen? This delightfully bobbled nudibranch with electric blue spots is sometimes seen among seagrasses and seaweeds on our Northern shores, as well as at Cyrene Reef. Often seen in numbers, and then not seen again for some time.

Features: 5-10cm long. Broad, soft body with lots of bumps and pimples, and distinctive electric blue spots. Thick club-like rhinophores and large feathery gills. The animal is generally beige sometimes with a purplish or pinkish tinge. Younger animals may be more colourful than older ones. Some members of this family can cause irritation to eyes and a burning sensation to the skin.

What does it eat? It eats sponges, possibly sponges that live in murky, mucky sites. It lacks a radula and jaws so it can't rasp or chew its food sponge. Instead, it secretes digestive juices onto the sponge and then sucks up the softened sponge. How is it the juices don't leak away into the surrounding water? Dr Bill Rudman explainshow structures around the mouth might help it form a seal around the feeding site.

Pulau Sekudu, May 05

Egg ribbon being laid.
Sisters Island, Apr 14

Mating pair?
Pulau Sekudu, Oct 11

Beting Bronok, Jul 07


Cyrene, Jul 09

Frilly gills.

Pulau Sekudu, Apr 06

Mating and laying eggs.
Photos shared by Loh Kok Sheng on his blog.

Blue-spot nudibranchs on Singapore shores

Photos of Blue-spot nudibranchs for free download from wildsingapore flickr

Distribution in Singapore on this wildsingapore flickr map

Tanah Merah, Dec 09
Photo shared by James Koh on his blog.

Pulau Semakau, Nov 07
Photo shared by Toh Chay Hoon on her flickr.

Kusu Island, Sep 10
Photo shared by Loh Kok Sheng on flickr.

Pulau Hantu, Jun 08
Photo shared by Loh Koh Sheng on his blog.

  • 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.
  • 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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