Spirobranchus kraussii (Baird, 1865)
Robust, up to ~30 mm
White tube, flattened top in cross section formed by 2 keels that extend over mouth as flap.
In life, radiolar crown with dark base (black, brown, blue, grey), with alternating light brown and white bands. Few with bright orange radioles. Radioles connected by inter-radiolar membrane for ~half length. Ventral surface of peduncle white with black stripes. Body brown or blue.
Peduncle with pair of smooth wings with pointed tips. Operculum slightly concave, no ornamentation.
Collar high, continuous with thoracic membranes, forms apron across up to 5 chaetigers. Thorax with 6 uncinigerous chaetigers, chaetae limbate, finely serrated, uncini with 10 or 11 curved teeth in single row. Abdomen with 1 or 2 achaetous segments anteriourly, up to ~90 chaetigers, uncini with 9 – 11 teeth in single row, ~half size of thoracic uncini, trumpet-shaped abdominal chaetae appear in last 5 – 25 chaetigers. No capillary chaetae.
Low to upper intertidal, often in rock pools
South Africa: Western Cape Province (Cape Point) to northern KwaZulu Natal.
Mozambique: to ~Xai Xai.
Part of species complex; taxonomy of species outside of southern Africa need resolution. Considered invasive in Mediterranean; taxonomy of these populations also need to be resolved.