Opisthobranch of the Week Data
Stiliger smaragdinus is considered to be very rare on Okinawa as I have seen and collected only a solitary individual over a period of many years of diving here. The featured animal was collected from an area of mixed sand and coral rubble. It was found amid a dense assemblage of miscellaneous "leafy" thallophytes (reds and greens), which were being collected for later inspection; unfortunately the animal wasn't discovered until after the dive and I was unable to determine which alga the animal was associated with. In a 1959 paper, Baba states that the animal is found living on the green alga, Caulerpa.
This is the first time Stiliger smaragdinus has been reported from Okinawa. Baba's original description (Opisthobranchia of Sagami Bay collected by His Majesty The Emperor of Japan) of the animal has it being originally found at a depth of 16m off Sajima, Sagami Bay, Japan. The lone Okinawan specimen was found in 62m.