Molgula manhattensis

Molgula manhattensis (De Kay, 1843)

Common Names

Sea grape

Languages: English



This species is a simple, solitary ascidian, that sometimes grows in dense clusters. The body is globular in shape, measures 1-4 cm in diameter, and attaches to the substrate at its base. The oral and atrial siphons are positioned anteriorly, and prominent when extended. Overall, the tunic is translucent to greyish-green in colour; the surface is covered with numerous tiny hair-like fibrils, often fouled with pieces of shell, algae, or sediment. A bean-shaped kidney is located on the right side of the body, and along with the reproductive gonads, is often visible through the tunic.

Author(s): Frey, Melissa
Rights holder(s): Frey, Melissa


Look Alikes

In the Northeast Pacific, Molgula manhattensis is most similar to to other molgulid tunicates, including M. pacifica (Huntsman, 1912), M. pugetiensis Herdman, 1898, and M. verrucifera Ritter and Forsyth, 1917; another non-native species found in the region, M. ficus (Macdonald, 1859); and in Alaska, M. retortiformis Verrill, 1871 and the recently documented M. citrina Alder and Hancock, 1848.

Author(s): Frey, Melissa
Rights holder(s): Frey, Melissa

Ecology and Distribution


Molgula manhattensis has been introduced to the Northeast Pacific, with confirmed records from British Columbia to California. In addition, this species has been introduced to several other locations around the world, including Australia, China, and Japan. In Great Britain and northern Europe, the species is considered cryptogenic. Its native geographical range includes the northeast United States from Maine to Louisiana.

Author(s): Frey, Melissa
Rights holder(s): Frey, Melissa


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Haydar, D., Hoarau G., Olsen J. L., Stam W. T., & Wolff W. J. (2011).  Introduced or glacial relict? Phylogeography of the cryptogenic tunicate Molgula manhattensis (Ascidiacea, Pleurogona). Diversity and Distributions. 17, 68-80.
Kozloff, E. N., & Price L. H. (1996).  Marine Invertebrates of the Pacific Northwest. 539. Seattle: University of Washington Press.
Lambert, C. C., & Lambert G. (1998).  Non-indigenous ascidians in southern California harbors and marinas. Marine Biology. 130, 675-688.
Lambert, C. C., & Lambert G. (2003).  Persistence and differential distribution of nonindigenous ascidians in harbors of the Southern California Bight. Marine Ecology Progress Series. 259, 145-161.
Ruiz, G. M., Fofonoff P. W., Steves B., Foss S. F., & Shiba S. N. (2011).  Marine invasion history and vector analysis of California: a hotspot for western North America. Diversity and Distributions. 17, 362-373.
Van Name, W. G. (1945).  The North and South American ascidians. Bulletin of the American Museum of Natural History. 84, 476 + plates. New York: Order of the Trustees.