Lots of jellyfish around this season, this specimen of 'Cyanea capillata' - Lion's mane jellyfish - is quite small compared to some I have seen.
Human encounters with the jellyfish can cause temporary pain and localized redness.
In normal circumstances, however, and in healthy individuals, the stings of the jellyfish are not known to be fatal; vinegar can be used to deactivate the nematocysts.
If there is contact with a large number of tentacles, however, medical attention is recommended after exposure.
The lion's mane jellyfish appears in the Sherlock Holmes short story "The Adventure of the Lion's Mane" published in The Case-Book of Sherlock Holmes.
Holmes discovers at the end of the story that the true killer of a professor who died shortly after going swimming (shouting "the lion's mane" before he succumbed) was actually this jellyfish.
Suspicion was originally laid upon the professor's rival in love, until the latter was similarly attacked (he survived, although badly stung). In the context of the story, it is only because the school professor has a weak heart that he succumbs, as is confirmed by the survival of the second victim.
