The Portuguese man-o-war is a species of siphonophores known by the scientific name physalia physalis. It is also known as bluebottle or bluebubble, and is actually a colony of four kinds of polyps.
Even though the Portuguese man-o-war may look like a jellyfish, and is usually thought of as a jellyfish, it is actually a siphonophore. A group of animals that is similar to the Portuguese man-o-war are the chondrophores, although the chondrophores have radial symmetry and do not have a siphon like the man-o-war. The Portuguese man-o-war has many tentacles that, if stung by one, can cause excruciating pain to humans. There have even been several deaths caused by their poison. The Portuguese Man O' War was created on the Fifth day of creation, along with all the other sea creatures and birds. 
The Portuguese man-o-war has bilateral symmetry, with tentacles at one end and the float at the top. It also has an air bladder called a pneumatophore, or sail, that causes it to float. Without any way to move itself, the Portuguese man-o-war is pushed around the surface of the ocean by the winds and current. The man o' war's sail is filled up with air, but can build up large amounts of carbon dioxide inside its sail. It must stay wet to survive, so it will often roll around to keep the surface wet. Below this float are long tentacles that can sometimes stretch over ten meters long. These tentacles can sting and kill small sea creatures using their poison-filled nematocysts and muscles to bring the prey up into the gastrozooids, which is another type of polyp that surrounds and digests the prey. The gonozooids are the polyps that reproduce.
The Portuguese man-o-war is a colony of polyps and medusa that are specialized for different functions. Each one is an individual, but their integration with one another is so great that the colony seems as though it is one large individual; and most of the zooids (medusa and polyps) are so specialized for their specific task that they would not be able to survive on their own.  The Portuguese man-o-war are hermaphrodites, so each individual gonozooid consists of male and female parts. The gonozoids of the man o’ war are the polyps that are responsible for reproduction. The adult medusa releases sperm which fertilizes an egg. The egg forms a larva, which finds a place to form into gonozooids. These polyp gonozooids eventually release a medusa form by asexual budding that grows into the adult medusa which started the cycle. 
The Portuguese man-o-war often has man-of-war fish (Nomeus gronovii) living within its tentacles for protection. The nudibranch glaucus atlanticus (blue sea slug) uses a gas filled sac to float, much like the man o' war, and being immune to the poison, feeds on the man-o-war as well as other neustons (minute organisms). The Portuguese man-o-war is an important source of food to the sea turtles that are immune to the poison. Some places you might find Portuguese Man O' War are on the coasts of North America, Africa, Europe, and Australia along with a few other places in the world. The Portuguese man-o-war was recently found as far north as Cape Cod, in Massachusetts.
Portuguese Man-O-War (Physalia physalis)
- Portuguese Man O' WarFrom Wikipedia, the free encyclopedia
- Days of Creation
- Bluebottle Australian Museum Online