Siphonophores are not actually jellyfish although siphonophores are related to jellyfish.
Siphonophores appear similar to that of jellyfish, and siphonophores also share the same phylum, Cnidaria with jellyfish, but they are technically a distinct type of colonial organism.
A siphonophore is a floating colony that is made up of thousands of specialized individuals called zooids.
And a jellyfish is a single organism.
The zooids are also genetically identical clones, although they are also so specialize for tasks like reproduction, feeding or movement that they can't survive alone.
The siphonophores are also hydrozoans, which are also often long and stringy or appear like a collection of specialized polyps, instead of the umbrella shaped, pulsing bell of a true jelly fish.
Some species of siphonophores like deep sea siphonophores form enormous chains in the deep ocean and can also be longer than a blue whale, which makes the siphonophores some of the longest animals on Earth.
The Portuguese man o' war is also often mistaken for a jellyfish, and this creature is a classic example of a siphonophore that consists of a gas filled float and tentacles.
Siphonophores are cnidarian animals of the hydrozoan order Siphonophorae.
And according to the World Register of Marine Species, the order of Siphonophorae, contains 194 species described thus far.
Siphonophores are highly polymorphic and complex organisms, which blur the line between individual organisms and colonial organisms.
Many siphonophores are harmful and capable of delivering painful, venomous stings similar to jellyfish, with the Portuguese Man-of-War being a well-known example.
While rarely fatal to humans, a siphonophores tentacles, which can extend over 100 feet in some species, contain powerful toxins designed to paralyze fish and can cause severe pain and skin welts.
A sting from a siphonophore is described as being excruciating and sometimes leaves, long lasting and burning welts.
The siphonophore can grow to lengths of 130 feet (40 m), longer than the blue whale, which is usually considered Earth's largest animal.
However the siphonophore's body is not much bigger around than a broomstick.