If you ever see a Portuguese man-of-war on the beach, the first thing to know is keep your distance: the jellyfish-like creature can deliver a painful sting whose venom will leave a welt that'll last for days (and don't turn to the classic Friends home remedy; it probably won't work, and may make things worse).
The second thing to know is that you're not looking at just one creature. You're looking at a whole bunch of them. The man-ofwWar belongs to a group of marine organisms called siphonophores, which are collections of genetically identical individual organisms that function together in a colony. Each individual organism is called a zooid, and is so specialized that it usually couldn't survive on its own.
The video above is from a series of images made by Aaron Ansarov, who himself is a former man of war: the Florida photographer spent nearly 15 years as a military photojournalist with the U.S. Navy. After moving back to Florida, he began capturing live Portuguese man-of-war and photographing them on a homemade light table (he releases them back into the ocean afterward). You can see him at work in this behind-the-scenes video (yes, that's his pyjama'd son observing the process):
And for a look at some of his extraordinary still photos of the creatures, see this National Geographic story.