Asteronotus cespitosus (van Hasselt, 1824)

The unmistakable species Asteronotus cespitosus is known from the Marshalls from five specimens. Three were found at a depth of about 3 meters in Kwajalein Harbor under a sheet of aluminum siding blown into the water by a storm. This and other aluminum debris that rest on the sand and Halimeda algae bottom under our moored boat have proven very fruitful as "nudibranch collectors." A number of other species are known from the Marshalls solely from specimens found under these few sheets of aluminum. Two more specimens were found together at low tide on an intertidal reef southeast of Roi-Namur Island in Kwajalein Atoll. Both this pair and the first pair found in the harbor were observed with egg masses.

The shot below shows the anterior end with the rhinophores.

Here is a close-up of the branching gills.

When found, the two animals had just deposited an egg mass on the sponge-encrusted undersurface of the aluminum sheet. This image is captured from video and is therefore not very clear.

The specimen below appeared to be a young one of these. It measured 50mm, about half the length of most of our specimens. It was found in a patch of Halimeda and other algae at a depth of 8m on 22 December 2008.

Created 15 December 2006
Updated 5 January 2009