Siphonophores

Photo borrowed fro the Monterey Bay Aquarium Website

I am reading a really interesting book called The Universe Below by William Broad. It was a random thrift store find, but totally worth the $1.50 I paid for it.
Anyway, one of the strange creatures that I discovered on my undersea travels are things called a siphonophores. I am fairly versed in at least the basic genera of the oceans, but when I came across these guys I had no idea anything like them even existed, and they are so weird and cool I just had to share!
The most well known siphonophores are Portugese Man-O-War (I thought they were a kind of jelly fish, and while they are related, they aren't the same thing), that float on the surface of the water and sting tourists as they wade in the ocean on vacation. But most siphonophores live in the middle of the water column, eating whatever happens to get in their path. They are gelatinous, and generally clear to opaque white. Most of them bioluminesce in dark water, some even flash red (in addition to the normal blue and green) to attract fish. Some are as long as 40 meters, and may have several stomachs and hundreds of thread-like tentacles trailing behind trolling for snacks.While they generally appear as one organism, usually they are a floating colony of many individuals, all of which were produced by the same fertilized egg.

Photo borrowed from siphonophores.com

Anyway check out this video on YouTube of a giant siphonophore. (You can find more links to videos if you do a search, but this was the best one.) Or you can read about them on Wikipedia.