Nembrotha cristata is sporadically common at Kwajalein Atoll, but was never located despite extensive searching at Enewetak. At Kwajalein, it can be found on seaward or lagoon interisland reefs, but it prefers lagoon pinnacles, where it lives in ledges and under rocks and eats a dark green colonial tunicate we have tentatively identified as Sigillina signifera. In September, 1998 and August, 2000, we saw dozens feeding on the green tunicates on top of a shallow (2 meter depth) lagoon pinnacle near Onemak Island. In September, 2002, and other more recent trips to the same pinnacle, there were none. More recently, another lagoon pinnacle near the southern end of Kwajalein Atoll was the site of almost an invasion of the dark green tunicate, which covered much of the bare rock on the reef. Soon after, numerous Nembrotha cristata and a few N. kubaryana were found feeding on the tunicate colonies. A year later, most of the tunicate was gone and no more nudibranchs were present. Populations do seem to come and go.
The large individual below was eating the small green tunicates near the lower right side of the photo.
Several were found on a lagoon pinnacle on 15 September 2013.
Feeding on the dark green colonial tunicate Sigillina signifera.
Juveniles may start off with red spots that slowly turn green. The photo below is from Stan Jazwinski.
Created 3 January 2007
Updated 17 December 2023