In 2006 and 2010, huge swarms of jellyfish invaded the beaches of Spain, stinging tens of thousands of swimmers. In some places, these occupying jellyfish appeared in concentrations of up to ten per square meter. These swarms are called "jellyfish blooms," and they're popping up in oceans worldwide like cam chat-room ads on free porn sites. Hawaii and Ireland were similarly swarmed in 2007, Israel and France in 2008, and Tunisia and Italy in 2009.
Don't start screaming now. You'll be hoarse by the end of the article.
Man-Sized Jellyfish: Nature's way of saying, "f**k right off, divers."