A small hydroid found aro und the world. It is usually innocuous, but in one small area of the northern Honshu island of Japan, and in a similar area on the opposite side of the Sea of Japan around Vladivostock, a sting causes severe systemic symptoms very similar to the Irukandji syndrome. Similar to Irukandji stings, Gonionemus stings occur in epidemics with more in some years than others. It has not caused a proven death, although some unproven deaths have been claimed in the past.... gonionemus
The taxonomic class including the plume-like hydroids, hard stinging “corals”, small jellyfish with bells (i.e. bell-shaped bodies), and members of the order Siphonophora which may be buoyed up by gaseous floats.... hydrozoa
Commonly known as fireweed, Lytocarpus is a stinging hydroid (hydrozoan) that grows on pilings, rocks and overhangs in tropical and sub-tropical areas of the world. Skin contact causes an itchy vesicular rash.... lytocarpus philippinus
The taxonomic group of hydroids that are not single animals, but colonies of animals. They may be either free swimming or floating, with or without a float. The genus of dominating medical importance is Physalia.... siphonophora
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