Prostomium rounded (sometimes weakly indented). Caruncle middle or end of chaetiger 3. 2-3 pairs of eyes. Live animals pale green with bright red branchiae and black pigment along edge of prostomium; faint black markings on dorsal surface between chaetigers 1 & 2 and 2 & 3. Preserved animals tan, dark line along the feeding groove of palps and along margins of prostomium and caruncle. Chaetiger 1 with short notochaetae. Hooded hooks start on chaetiger 7; up to 7 or 8 per ramus. Neuropodial lobe with hooded hooks up to chaetigers 10 or 11. Modified spines of chaetiger 5 with two heavy curved spines and three blunt, bristle-topped spines. Branchiae on chaetigers 2-4 and posteriorly from chaetiger 6, absent from last chaetigers 2-10 chaetigers, filiform, separate from notopodial lobes. Large paired glands with many small glandular pouches in chaetigers 7-9. Pygidium a fleshy cuff with dorsal notch, may be divided into four lobes or by folds in the pygidium.
Largest specimen: up to 33mm
South Africa: Saldanha Bay to Haga Haga, cultured abalone, restricted distribution in Western Cape outside farms
Southern California (Type locality) to Canada (British Columbia).
Australia, Hawai’i, New Zealand, Argentina, Spain, United Kingdom, Japan.
Primarily a sediment dweller. Secondary borer on cultured abalone in South Africa, may form tubes on shells of oysters Ostrea edulis and Crassostrea gigas, the barnacle Balbnus cariosus and abalone Haliotis roei.
Worms reproduce throughout the year, but increase from end of winter to early summer in South Africa. Poecilogonous; individual tear-drop shaped capsules contain adelphophagic and planktotrophic larvae.