<P> The lion 's mane jellyfish ( Cyanea capillata ) , also known as the giant jellyfish or the hair jelly , is the largest known species of jellyfish . Its range is confined to cold , boreal waters of the Arctic , northern Atlantic , and northern Pacific Oceans . It is common in the English Channel , Irish Sea , North Sea and in western Scandinavian waters south to Kattegat and Øresund . It may also drift in to the south - western part of the Baltic Sea ( where it can not breed due to the low salinity ) . Similar jellyfish -- which may be the same species -- are known to inhabit seas near Australia and New Zealand . The largest recorded specimen found washed up on the shore of Massachusetts Bay in 1870 , had a bell with a diameter of 2.3 metres ( 7 ft 6 in ) and tentacles 37.0 m ( 121.4 ft ) long . Lion 's mane jellyfish have been observed below 42 ° N latitude for some time in the larger bays of the east coast of the United States . </P>
which is the lion 's mane jellyfish 's species within its genus
capillata