Body
Up to 39mm long. Smooth, translucent white, revealing pale dull orange or pinkish digestive gland below gills, and white buccal mass below rhinophores [image5]. White penis extrudes behind right rhinophore [8]. Yellow medial dorsal ridge on posterior third of body [2]. Reduced mantle rim on each side, from below rhinophores to by gills, marked discontinuously yellow or gold [12]. Anterior of rim usually has triangular lateral projection [2]. Posterior of rim produced into single, large, white, yellow-tipped, erect, elongate process which shields the gills. Other markings very variable; sometimes restricted to dorsal row of yellow or gold marks [5], usually also some on flanks [12], and occasionally many longitudinal rows of yellow marks. Sometimes, black marks also, ranging from a small patch [10] on the rhinophore to multiple lines and areas of black [3]. Some specimens have all markings orange, others randomly dappled yellow, gold, orange and black, and some have intricate patterning [13]. Frequency of different colour combinations varies; some shores have black on nearly all specimens, others none.
Rhinophores
Basal third smooth, translucent white. Upper two thirds have up to 15 prominent lamellae [11], lower ones incomplete. Middle third flexed backwards, translucent white with yellow pigment on anterior. Distal third flexed forwards, yellow, except translucent white tip. Extent of yellow may vary, and some also have black pigment [10].
Gills
Fan of seven, sometimes nine, white, simply pinnate gills, with yellow pigment distally, around dorsally situated anus [2]. Some also have black and orange pigment. Gill fan can be folded backwards to conceal anus [9]. When defecating, it can be held vertically to avoid fouling of gills [8].
Head
Anterior edge extended into a veil with four [6] to six [2] elongate yellow processes. Semi-circular oral area has a curved perpendicular white flange at each side [6].
Foot
Translucent white with well defined, dorsally yellow, propodial tentacles [6]. Yellow medial line on tail shows through translucent sole. Viewed dorsally, body may conceal foot, or foot may spread laterally into view [9].
Polycera faeroensis
- No elongate papillae at base of rhinophore.
- Oral veil with six to twelve yellow elongate processes.
- No medial dorsal pigment marks between gills and rhinophores.
- Anterior of foot expanded into propodial tentacles.
Trapania maculata, T. pallida & T. tartantella
- One or two backward pointing elongate papillae at base of each rhinophore.
- One elongate papilla on either side of the gills.
- Anterior of foot expanded into propodial tentacles.
- Two forward pointing elongate papillae at base of each rhinophore.
- No yellow elongate processes on anterior edge of head (but has white oral tentacles)
- Several erect elongate papillae on either side of the gills.
- No propodial tentacles or extension on foot.
On lower shore and sublittorally to 60m. Large and most easily found in February and March. Feeds on Electra pilosa (often on Fucus serratus) (EML), Membranipora membranacea (often on Laminaria) (EML), Callopora dumerilii, Celleporella hyalina and Tegella unicornis. Simultaneous hermaphrodite. Short curved ribbon of spawn attached by edge to Fucus and Laminaria fronds in most months. Shelled veliger larvae live as plankton before metamorphosing.
Arctic to Mediterranean. (GBIF map). Common, and sometimes abundant in early spring, on hard substrate shores all around Britain and Ireland. (U.K. interactive distribution map.NBN.)
Alder, J. & Hancock, A. 1845-1855. A monograph of the British nudibranchiate mollusca. London, Ray Society.
Thompson, T.E. & Brown, G.H. 1984. Biology of opisthobranch molluscs 2. London, Ray Society.
Current taxonomy: World Register of Marine Species (WoRMS)
Irish distribution maps and prey organisms:
Picton, B.E. & Morrow, C.C., 2010. Encyclopedia of Marine Life of Britain and Ireland (EML)