Picture of the Week—Portuguese Man o’War

Feedloader (Clickability)

What is it? A beaded necklace? Red blood cells? No, it's the Portuguese Man o'War (Physalia physalis), magnified 30 times. Though it resembles a jellyfish, the Portuguese Man o'War is a siphonophore, a colony of organisms that work together. The sting of the venom in the tentacles' nematocysysts is incredibly painful, though rarely deadly. This photo, taken by Alvaro Migotto of the University of São Paulo in Brazil, won 6th prize in the 2009 Olympus BioScapes Interational Digital Imaging Competition.

Notorious for its painful, powerful sting, the Portuguese Man o' War has a gas-filled floating chamber that supports the tentacles, which bear sting cells. Shown are the pink batteries of stinging cells and a delicate muscular band responsible for the high contractibility of the tentacles.

Check out the entire collection of Pictures of the Week on our Facebook fan page.

(Hat tip: Transcription and Translation)

Get the latest Science stories in your inbox.