Clubbed Tunicate, or styela clava, is a solitary tunicate with a cylindrical, club shaped body up to 18 cm long. It is brown or tan-white in colour with a tough stalk which is about one third the length and also has as a tough, bumpy, wrinkled tunic (outer skin). Incurrent and excurrent siphons are short, closely spaced and near the tip of the organism.
This tunicate grows on any floating or submerged substrate particularly artificial structures like pilings, aquaculture gear, floats and boat hulls that are located in the lower intertidal to subtidal zones. It often grows with or on other fouling organisms.
(Photo credit: D. Mouland, DFA)
Clubbed Tunicate is a hermaphroditic broadcast spawner but it can not self-fertilize. Eggs and sperm are released when temperatures are above 15°C and can stay in the water column for 1 to 3 days. Larvae are free-swimming for 1 to 3 days.
This species is native to the Northwest Pacific Ocean, mainly Japan and Korea.
Means of introduction
The Clubbed Tunicate is thought to be spread mainly through hull fouling. Since it is a broadcast spawner eggs or larvae may also be transferred through the release of bilge or ballast water.
Management of the species
Fish and shellfish harvesters should avoid transferring harvested shellfish and fishing gear to another area. Gear should be thoroughly dried before transfer. Boat hulls should be inspected and, if necessary, thoroughly cleaned and disinfected with bleach or vinegar then dried before moving to other areas. Any organisms removed from boat hulls or gear should be disposed of on land. Bilge water should be released on land or disinfected. Report sightings by using the contact information on the main AIS page.