A widespread tropical Indo-West Pacific species. Burrows on intertidal and subtidal coral sand.
Shell length: 20mm. Koumac, northern New Caledonia, October 1993. PHOTO: Bill Rudman.
The acteonids are some of the most primitive of the opisthobranchs, having a very "snail-like" appearance, with a prominent shell, an operculum, and a relatively small colourless animal.
Note the posterior flaps on the head, which form the "headshield" which give them the name "cephalaspid".
Despite their "primitive" body plan, they are in fact highly specialised, feeding on polychaete worms.
• Gmelin, J.F., (1791). In: Linnaeus, C., Systema Naturae, Ed.13. 1(6): 3021-4120.
Rudman, W.B., 1998 (December 18) Pupa sulcata (Gmelin, 1791). [In] Sea Slug Forum. Australian Museum, Sydney. Available from http://www.seaslugforum.net/factsheet/pupasulc