We have seen Coryphellina exoptata in a variety of locations at Enewetak and Kwajalein Atolls, including lagoon reefs, pinnacles, and on the seaward reef. Like Pteraeolidia semperi, it is most easily found in the normally extremely rough windward seaward reef groove and spur system at depths of 2 to 5 meters. There is good hydroid growth in this area, but it wouldn't seem that any small nudibranch could hold on well enough to live there in the normally very surgy conditions. They must have a better grip than I would expect. It is also relatively common on the western seaward reef in overhangs or on the sides of rocks at or just below the knee of the dropoff at depths of 8 to 15m. We have seen individuals up to about 21mm long. In the first photo below, the nudibranch seems to be gliding along off the bottom; it is actually crawling on the tops of the filamentous algae growing on the substrate. The first specimen below is from Enewetak Atoll.
The specimen immediately below was photographed on Kwajalein Atoll's western seaward reef at a depth of about 10m on 10 November 2007.
The two specimens below were photographed on Kwajalein Atoll's western seaward reef at a depth of about 10m on 30 March 2008 and 18 April 2010. The lower shot was captured from video.
Created 8 January 2007
Updated 17 March 2024