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Invasive Species Altert – Freshwater Jellyfish

September 12th, 2013 | by

Freshwater jellyfish (also known as peach-blossom jellyfish) are newly recorded in Ireland since August 2013 (in Lough Derg and Lough Erne) but as of yet has not been recorded in other Irish freshwaters. The jellyfish is native to the Yangtze River Valley in China. The species was initially discovered in exotic aquatic plant tanks in Regent’s Park, London in 1880 but has since spread widely throughout the globe.

Experience in other countries suggests that blooms of these jellyfish occur only sporadically in warm water conditions and that they last, in any one year, for only a few weeks. Although it is uncertain what impacts the freshwater jellyfish will have on our native aquatic species, they do not appear to have any significant effect on the biology or ecology of the waters that they have colonised in other countries.  This is probably due to their sporadic occurrence and the short duration of their blooms. The freshwater jellyfish is not harmful to humans.

  • The jellyfish is translucent with a distinctive white/greenish cross and a white/cream circular outline and ranges in size from 5 – 25 mm.
  • It possesses in the region of 50 – 500 tentacles of varying length, the majority of which are relatively small.
  • There are two distinct life stages; one is a tiny attached polyp and the second is the medusa stage (free-swimming jellyfish). The inconspicuous polyp buds off medusa under warm water conditions (≥ 25oC).

Download the follwoing altert as a PDF: Freshwater Jellyfishjellyfish


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