Opisthobranch of the Week Data
Nembrotha milleri is named after Michael D. Miller (Gosliner, & Behrens, 1997), an accomplished underwater photographer and "brancher" extraordinaire. The animal can be distinguished by its shiny, satin, gray-green body color and is, at best, difficult to photograph as the color and velvet-like nature of the body seems to absorb a great deal of the light, making for a frequently underexposed photo. Mike Miller has a terrific photo of the animal on his Slug Site which nicely illustrates the body texture of this relatively large polycerid.
Nembrotha milleri is considered to be common, at least in the waters of Okinawa's Kerama Islands Group, which are located 30 ~ 40 kilometers west of the Okinawa capitol, Naha. I've not personally seen any of these animals in the waters of the main island of Okinawa, however, Atsushi Ono reports seeing in excess of 100 individuals, ranging between 30 & 150mm; on a single dive in March of 1998 Atsushi reports seeing a score or so of the species, which were however eaten by Roboastra luteolineata (pers. comm.).
The above featured animal was found on a large rock with nearby tunicates. It's not apparent if this animal was in fact feeding on the tunicates in the photo, and Gosliner & Behrens (1997) report in their species description that the species has not been found in association with any specific prey. However, in a Sea Slug Forum comment to Mary Jane Adams concerning a tunicate associated with N. milleri in the Solomon Islands, Bill Rudman (2000) quotes Dave Behrens as follows:
"Yes, this is the species of tunicate we always find N. milleri feeding on in the Philippines. The type locality, Devil's Point, Batangas Region, Luzon, Philippines is covered with this colonial ascidian, which we have had identified as Sigillina signifera".
Previously I've featured several members of the genus Nembrotha on these pages and as of the current date, there are several described and undescribed species reported from Okinawan waters. These featured animals are as follows:
N. guttata N. kubaryana N. lineolata N. livingstonei N. milleri (the above featured animal) N. species 1