The head has a short, stout snout with a large mouth. Large, extendible, outer lips have a gap ventrally which can be held closed (1) or open (2). The lips are thin and flimsy when extended, but are reinforced internally by longitudinal ribs (3) that, when held together, contract the outer lips and cause the edge to pucker (4).
A pink, internal odontophore (5) can be seen through the translucent, white head. The odontophore is separated from the outer lips by the yellowish inner lips that open laterally and close to a vertical line (6).
When viewed ventrally through the tentacle, the broad internal pigment spot of the eye is faintly discernible (7).
APPENDIX re range advance/retreat: flic.kr/p/2jW74ig