Styela clava

Styela clava
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Tunicata
Class: Ascidiacea
Order: Stolidobranchia
Family: Styelidae
Genus: Styela
Species: S. clava
Binomial name
Styela clava[1]
Herdman, 1881
Wikispecies has information related to: Styela clava

The stalked sea squirt (Styela clava), also known as the club sea squirt, club tunicate, Asian tunicate, leathery sea squirt or rough sea squirt, is a solitary, hermaphroditic, ascidian tunicate that is native to the Pacific coast of Asia, ranging from the Sea of Okhotsk to Japan, Korea and northeast China.[2][3] It has been introduced widely around the world such as off Australia,[4] New Zealand,[5] both coasts of North America,[6] and Europe.[7] It is considered invasive outside the native range, as adults lack natural predators, can outcompete native animals, feed on their planktonic larvae, and foul fishing gear and boats.[2][3] In the most extreme cases, it can reach densities of up to 1,500 per square meter (140 per square foot).[2]

Styela clava is a hardy species that can live at temperatures between −2 and 27 °C (28–81 °F), but only breeds above 15 °C (59 °F). Additionally, adults can survive in both marine and brackish water at salinities down to 10 ppt, although breeding only occurs above 25 ppt.[3]

These sea squirts are characterized by their brown or yellow, rough and wrinkled surface. They typically have a length of 8–12 cm (3.1–4.7 in), but can reach up to 20 cm (7.9 in).[3] They can be found on virtually any hard surface (such as rocks, buoys, pilings and shells of mussels) and occasionally on seaweed.[3] It may have been carried to New England waters from Europe (where it arrived in the early 1950s) in ballast water or ship fouling.[8]

Styela clava is called mideodeok (미더덕) in Korea where it is eaten[3] and part of the local dish agujjim.


Populations around Los Angeles, California grow 1–1.5 cm (0.4–0.6 in) per month in the first half year, reaching maturity and slowing growth at about 9 cm (3.5 in) in size. Broadcast spawning occurs late spring to early fall. They occur to a depth of at least 25 m (82 ft), and filter approximately 150 mL of water / minute / gram body weight.[9]


  1. "Styela clava". Integrated Taxonomic Information System. Retrieved February 17, 2007.
  2. 1 2 3 Global Invasive Species Database: Styela clava. Retrieved 21 April 2016
  3. 1 2 3 4 5 6 The Exotic Guide: Styela clava. Retrieved 21 April 2016.
  4. Hewitt, C.; et al. (1999). "Marine biological invasions of Port Phillip Bay, Victoria.". Centre for Research on Introduced Marine Pests CSIRO Technical Report (20): 344.
  5. Davis MH and Davis ME (2006). "Styela clava (Tunicata: Ascidacea) a new edition to the fauna of New Zealand.". Porcupine Marine Natural History Society Newsletter. 20: 23–28.
  6. Wonham MJ and Carlton JT (2005). "Trends in marine biological invasions at local and regional scales: the Northeast Pacific Ocean as a model system.". Biological Invasions. 7 (3): 369–392. doi:10.1007/s10530-004-2581-7.
  7. Davis MH and Davis ME (2005). "Styela clava (Tunicata: Ascidacea) a new edition to the fauna of the Portuguese coast". Journal of the Marine Biological Association of the United Kingdom. 85 (2): 403–404. doi:10.1017/S002531540501132Xh.
  8. RH Morris, DP Abbott & EC Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press: Stanford, CA. p. 207-208.
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