This small species was found rarely at Enewetak Atoll until a few months after typhoon Pamela in November 1982 blew away a number of corrugated aluminum buildings on Enewetak Island and scattered some of the aluminum sheets over the Enewetak's shallow lagoon reef. This particular reef was already a good spot for nudibranchs, with little live coral but lots of dead, sponge-encrusted table corals broken up by a previous storm some years before. A few months after typhoon Pamela, these aluminum sheets were developing a nice growth of sponges and other encrusting organisms on their undersides, providing a favorable habitat for nudibranchs. Sightings of many species increased in early 1983, and many species were common at least until the end of September, when the US Department of Energy closed the Mid-Pacific Research Lab on Enewetak and we all had to depart. In the nearly two years before April 1983, I saw only 4 specimens of Thorunna daniellae. In the 6 months from April to September, I counted 48 of them, mostly on this one reef. Since then, we have seen a few at Kwajalein as well, on lagoon reefs and pinnacles and in a Kwajalein reef quarry. Twenty-five measured specimens ranged from 6 to 20mm in length.
A group of four grazes on a thin encrusting brown sponge under a submerged piece of aluminum debris.
The two shots of a Kwajalein specimen below show its hitchhiking commensal copepod. Also note the purple on the oral tentacles on the photo immediately below.
The light-colored specimen below was found in a lagoon Halimeda patch on 4 August 2008.
The specimen in the two photos below was found on a Kwajalein Atoll lagoon pinnacle at a depth of 9m under a rock on 26 December 2008. The lower one shows the translucent sides of the foot.
Those below were found in a carpet of algae and some sponge at the base of the Kwajalein lagoon slope at about 32m on 24 December 2011.
Created 3 January 2006
Updated 4 February 2012