Cnidaria
The siphonophore belongs to the phylum Cnidaria.
No, the siphonophore belongs to a different phylum - cnidaria, along with jellyfish; the chiton is a mollusc, phylum molluscae along with snails and bivalves.
Giant Siphonophore
The longest animal on earth will surprise you it is not a whale it is a siphonophore (sy-FON-uh-for). A siphonophore is a jelly fish that can can have tnetacles that are 131 feet long!
A Portuguese man o' war doesn't actually "bite" people, but rather stings them with its tentacles. The sting can be painful and cause skin irritation, but it generally is not life-threatening. It's important to seek medical attention if stung, and to wash the affected area with salt water (not fresh water) to help alleviate the pain.
(Portuguese) man of war is Physalia physalis, a siphonophore hydrozoan. Or, a jellyfish.
The Portuguese man-of-war belongs to the phylum Cnidaria.
This jellyfish actully isn't a jellyfish they are a Siphonophore, that meanis it's made up of 4 different colonies of polyps. The navigation colonie helps but the wind mostly does all the work to make it move.
Predators of jellyfish include fish, sea turtles, pelagic crustaceans, cephalopods, comb jellies, other jellyfish, sea butterflies, pelagic nudibranchs, siphonophore cnidarians, humans, and occasionally, starfish and sea anemones.
According to wikipedia: They are commonly but erroneously thought of as a jellyfish. In fact, a Portuguese Man O' War is not a single animal, but rather a siphonophore - a colony of four kinds of minute, highly modified individuals, which are specialized polyps and medusoids[1].
A Portuguese Man'o War, Physalia physalis, is the best known siphonophore hydrozoan cnidarian. It is a colonial cnidarian that floats at the surface of tropical and subtropical oceans by means of a highly modified, gas-filled polyp. It is also infamous for its powerful venomous sting.