April 16, 2001
From: Scott Johnson
Attached are three Noumea decussata for the Forum. The species was relatively common along one shallow subtidal reef at Enewetak Atoll, Marshall Islands, where it shared the habitat with the similar looking N. simplex. I'm embarrassed to say that for some time I did not properly distinguish between the two species. Once I finally did, it became apparent that while N. simplex fed on a pink sponge, N. decussata preferred a species of yellow encrusting sponge. I believe the egg mass in the upper right photo was deposited by that animal.
Johnson, S., 2001 (Apr 16) Noumea decussata from the Marshall Ids. [Message in] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/find/4174
With help from you all I am gradually getting most of the species of Noumea on the Forum. Still a few to go, but we are getting there.
I am glad you found a distinction in the food sponge of N. simplex and N. decussata. Although quite a few species apparently share the same food sponges, it does help when we can make such a distinction. Examples like yours help illustrate the value of keeping an eye out for biological information when hunting and photographing nudibranchs.