Styela clava Herdman, 1881
This species is a simple, solitary ascidian, with a tough outer covering or tunic. The body is elongated and club-shaped, and attaches to the substrate by a distinct stalk. The stalk is shorter than or equal to the body length; total length measures 5-15 cm. The oral and atrial siphons are positioned anteriorly, smooth in texture, and ringed in alternating light and dark bands. The tunic is opaque, thick, and leathery, with distinct tubercles near the siphons and wrinkled pleats that run longitudinally. Overall colour ranges from brown to reddish-brown.
In the Northeast Pacific, Styela clava is most similar to to other styelid tunicates, including S. coriacea (Alder and Hancock, 1848), S. gibbsii (Stimpson, 1864), S. montereyensis (Dall, 1872), S. truncata Ritter, 1901, S. yakutatensis Ritter, 1901, and two other non-native species found in the region, S. canopus (Savigny, 1816) and S. plicata (Lesueur, 1823).
Styela clava has been introduced to the Northeast Pacific, with confirmed records ranging from British Columbia to Baja California, Mexico. In addition, this species has been reported from several other locations around the world, including the Atlantic coasts of Canada and the United States, Great Britain, Europe, and New Zealand. It is native to the Northwest Pacific, with a geographical range from southern Siberia and Japan to northern China.