Authorship details
Rudman, W.B., 2002 (November 24) Algae . [In] Sea Slug Forum. Australian Museum, Sydney. Available from

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Hawaiian Nudibranch?

November 27, 2002
From: Bradley Wm. Bowen

This nudibranch was observed hiding deep within the recesses of a partially dead coral head lying on a sandy bottom with simiar coral heads in the surrounding area for approximately 100 feet along the Kona Coast of Hawaii in May 2002. Depth was roughly 30 feet and the coral head was roughly 150 feet from the shore, where there was strong surge up to 40 feet from shore due to crashing surf. Because the nudibranch was so far in the coral head, this was the best angle that I could achieve with my camera. If you can identify the species I would appreciate it.
Bradley Wm. Bowen

Bowen, B., 2002 (Nov 27) Hawaiian Nudibranch?. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from

Dear Bradley,
Bill asked my advice on this photo as he wondered whether it was an algae, and thought I might recognise it from my time spent in Hawaii. It looks to me like the red alga Predaea weldii. I checked the book Seaweeds of Hawaii by William H. Magruder and Jeffrey W. Hunt. Their photo of Predaea weldii is small but it appears to be the same stuff. Their description of the species is as follows:
"Predaea weldii is found in subtidal habitats, where it grows between the branches of corals, reaching a length of 5 cm. It is extremely soft and gooey, turning into a shapeless blob when out of the water. Although not usually abundant, this seaweed is quickly noticed because the tips of its branches are fluorescent red." - Magruder, W.H. & Hunt, J.W. (1979) Seaweeds of Hawaii. Oriental Publishing Co., Honolulu. 116pp.

Actually, I remember the tips as more orange, similar to the colors of the image you sent.
Best wishes,
Scott Johnson

Johnson, S., 2002 (Nov 27). Comment on Hawaiian Nudibranch? by Bradley Wm. Bowen. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from