Doriopsis pecten is easily recognized by its dark blue body. It is nearly always found on a dark blue sponge Terpios granulosa, upon which it is very hard to see. It is possible that the earlier name of Doriopsis viridis Pease, 1861, should be given to these animals, but this latter species is reported to be green in color. The two species have generally been considered to be different, and both have been reported from Enewetak Atoll in the Marshalls by Young (1967), but I am not sure I can tell them apart. All but one (near the bottom of the page) of the many specimens we have observed here in the Marshalls have been mostly blue in color, although a few had a faint greenish tinge. They live mostly in the intertidal and very shallow subtidal, but we have seen specimens down to a depth of about 8 meters. Twelve measured specimens ranged from 3 to 15mm in length.
The next photo shows the peculiar gills of species of Doriopsis.
Often the nudibranch blends in so well on its normal food sponge, the only way it gets noticed is by the presence of egg masses in the vicinity, which are, as in the photo below, usually not deposited directly on the prey sponge. The two egg masses here are probably just different ages; it is likely the lower one was put down first and the developing larvae may be getting ready to hatch out. This photo was shot in 1982 at a depth of about 4m on the lagoon side of Enewetak Island, right off the beach fronting the Mid-Pacific Research Lab.
On 22 February 2009 on a shallow lagoon reef at Kwajalein, I (SJ) spotted the yellow egg mass at left and another, more gray colored egg mass out of the frame, under a rock at a depth of about 5m. Scanning over the rock, I spotted the tiny 6mm bluish green Doriopsis a short distance away. I did notice there was none of the blue sponge prey D. pecten is usually found with on this rock at all. I shot a few still images with my video camera and went on my way. Only when processing the images that evening did I notice the yellowish orange nudibranch on the yellow orange sponge barely a nudibranch's length away. I presume that is a color form of the same species, and has taken its color from the sponge. The yellow orange sponge does look as though it has been grazed. I would like to have looked at this a bit closer. Are we seeing one or two species here? Is one or both the real Doriopsis viridis? Alas, no way to tell now.
A closer view of the two nudibranchs.
Below is a closer shot of the bluish green individual in the photo above. The green color is fairly distinct.
The specimen below was large for this area at about 15mm long. Just to right of the animal is what appears to be a whitish patch of rock that the nudibranch grazed the blue sponge from.
It seems the more of these I see the less I understand. A pair of Doriopsis specimens found on 31 December 2010 just makes the waters muddier. Two nudibranchs, one greenish and one dark blue, were under a dead disk of Fungia coral along with an egg mass. Both nudibranchs had distinctly yellow feet, as seen in a couple of the closeups below. Yet, the egg mass does not really seem to match the ones from Enewetak above (third photo from top on this page) although zooming in the different egg masses (separate page) show they may not be all that different.
D. pecten is also common in Hawaii.
Created 11 December 2006
Updated 6 April 2011