Mnemiopsis leidyi

Mnemiopsis leidyi - Sea Walnut

Habitat Waters of varying salinity including estuaries at a depth of no more than 40 meters

Range East Coast of North and South America, especially between Cape Cod in Massachusetts and Cape Hatteras in North Carolina

Description Oval-shaped, somewhat flat, transparent invertebrate roughly 10 cm in size. Green bioluminescence as a defense mechanism when threatened.

Ecological Notes The trophic effects of these ctenophores have been discovered through their migration across the Atlantic to the Black Sea in the 1980s, where they became an invasive species. These sea walnuts, or comb jellies, feed on zooplankton, fish eggs, and fish larvae and overfeeding caused several European fisheries to close. The sea walnuts were eventually moderated by the migration of another western Atlantic ctenophore, Beroe ovata, which is a predator of Mnemiopsis leidyi. This species can reproduce either sexually or asexually. The specimen lays eggs and typically breeds between May and July.

Personal Information An abundance of these comb jellies were found while trawling in the Croatan Sound near the University of North Carolina Coastal Studies Institute. The specimens do not sting and are harmless to touch.

References

http://eol.org/pages/393337/details

http://ocean.si.edu/ocean-photos/sea-walnut-mnemiopsis-leidyi

Additional Information

Haraldsson, M., Bamstedt, U., Tiselius, P., Titelman, J., Aksnes, D.L. 2014. Evidence of diel vertical migration in Mnemiopsis leidyi. PLoS One. 9(1).

This paper investigated the potential links between horizontal and vertical dispersion of this species in relation to trophic effects. Mnemiopsis leidyi are very tolerant of salinity and temperature changes, and their migratory habits allow them to be so tolerant.

Didžiulis, V. (2013): NOBANIS – Invasive Alien Species Fact Sheet – Mnemiopsis leidyi. – From: Online Database of the European Network on Invasive Alien Species – NOBANIS www.nobanis.org, Date of access 5/3/2016.

Because sea walnuts were an invasive species, much research was completed and compiled regarding its distribution, migration, and ecology. Here, the economic effects were studied and recommendations were made about how to reduce the species abundance.

Contributed by Alyssa Predota - 2016

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