Eubranchus pallidus (Alder & Hancock, 1842)

2 March, 2013.
Glas Eilean, Loch Fyne on the west coast. 
15 mm animal on a hydroid at 18 m. Water temperature 7°C.
Sony NEX-5 in Nauticam housing, 18-55mm lens, SubSee +10 dioptre and 2 x Inon D-2000 flashes.