Bicellarina alderi

Bicellarina alderi is an erect, dichotomously branched bryozoan. Colonies form delicate straggling tufts about 4 cm high which are white/transparent in colour. Autozooids alternate and are contiguous, but loosely connected, for most of the length. At the extremities autozooids may be altogether separated. Autozooids are horn-shaped; long, cylindrical and very slender at the proximal end (closest to the colony origin). They are typically 1.1 – 1.3 by 0.35 – 0.4. There is usually 1, but sometimes 2, long, slender curving spine arising from the outer edge of the autozooid.

The species is able to colonise shells, stones, hydroids and gorgonians from fairly deep water. It is known from 6 m, but is more common between 50 – 1000 m.

Bicellarina alderi is a boreal-Atlantic species, known from Shetland, and the continental slope, west of Ireland. It extend from Britain and the Kattegat to Bear Island and Greenland.