Body (excluding appendages)
Numerous. Arranged along sides and across anterior and posterior of body, completely surrounding, and sometimes partially concealing, the dorsum.
Many wart-like papillae on surface, and one on apex . Translucent whitish, shading to hyaline green basally , hence J. hyalinus from Latin hyalus = glass green. Lateral cerata have a brown internal digestive gland extending half way up, or less . Those across the posterior, and those anterior to the rhinophores, have no digestive gland. Many small flecks and streaks of brown, white and yellowish white pigment on surface.
Truncated apex. Numerous elongate rib shape warts orietated obliquely along the rhinophore. Brown with much yellowish white freckling, especially on warts. Similarly coloured large wrinkled caruncle between the bases of the rhinophores .
Partly covered with cerata. Seen from below; a small oral veil, translucent white freckled yellowish white, extends laterally into oral tentacles . Mouth yellowish white. Small eye at base of each rhinophore.
Broad until posterior of body, from where the projecting metapodium tapers rapidly . Bilaminate anterior edge smoothly rounded with no propodial lobes or tentacles. Sole transparent whitish, clearly revealing internal anatomy and the white freckles on the dorsal surface of the foot .
- Surface of cerata smooth
- No caruncle between rhinophores.
Most records sublittoral, on or near its erect bryozoans prey; species of Bugula (EML) and Scrupocellaria (UWN). When contracted, resembles a sea anemone . Both in extreme exposure (e.g. St Kilda) and extreme shelter (e.g. Lough Hyne). A relatively agile species with near neutral buoyancy, so very occasionally drifts on shore where it may be found in pools or in shallow water. Simultaneous hermaphrodite. Spawn a coiling line of white ovoids, each of which contains many ova , recorded September in wild, and May in refrigerator at 9° C.