B. gracilis colonies are generally pale yellow to tan in color and form tangled masses in hydroids, algae, seagrasses, or other substrata (Winston 1982). Zooids are tubular in shape and are attached basally to the stolon where they are arranged either alone, in pairs, or in clumps. Stolon width measures approximately 0.05 mm in diameter. Individual zooids differ in size depending on whether the lophophore is extended or not, measuring approximately 0.6 mm X 0.12 mm while expanded. Retracted zooids are shorter and are generally observed to be flattened against the substratum. The lophophore is not pigmented and measures approximately 0.315 mm in diameter. It bears 8 tentacles and shows a great deal of flexibility while actively feeding (Winston 1978).