Many of the creatures we call Jellyfish are not true jellyfish, so the following is based on common descriptive terms rather than Genus or Scientific classification.
The Large Box Jellyfish, or Chironex Fleckeri and the two recently classified types of tiny thumbnail sized Irukandji,Carukia barnesi and Malo kingi , are the uncontested contenders for the most venomous creatures in the animal kingdom. More research is being conducted to accurately classify the Irukandji venom as, unlike the Box Jellyfish, Irukandji venom is much slower in its' affect on humans, but severe and life threatening symptoms last many times longer from a fraction of venom in comparison to the amout of venom from the Box Jellyfish.
The Moon Jellyfish is the most common type of jellyfish. The Black Medusa and the Big Red are both deep sea jellyfishes with the Big Red being the largest jellyfish in the world with a bell diameter of about 3 metres.
The Blue Bottle, or Portuguese Man-O-War, is possibly the oddest in the so-called jelly fish arena. It is made up of many separate creatures called Zooids which have their own different role to play in the life cycle of the colony, including providing feeding parts and stinging cells to be brief. It has an air sac which it uses to float on the surface of the water and is carried by the the wind while dangling its tentacles in search of food by other Zooids that have sensory cells to detect nearby prey. The large Blue Bottles can have a body of over 15cm (6") long and tentacles over 10M (33') long.
There are many more varieties in this loosely called jellyfish family that cluster in their millions, fresh water jellies, some are unique to the deep chasms of oceans, and some that emit light and put on brilliant strobe like shows. Some have many sets of complex eyes with lenses and some actively seek out and chase their prey.
Most consensus in the scientific world is sure there are yet undiscovered species just as spectacular if not more so.
Box Jelly Fish
The commonly known box jellyfish is a stinger that can kill and is internationally recognized. It is from the Chirodropid Jellyfish family. Chirodropid jellyfish usually have multiple tenticles hanging from each corner of their box shaped bodies and usually have stinging cells only on their tenticles. Another two types are: * Chironex fleckeri * chiropsalmus The not as well known, but just as deadly Irukandaji is also found in Australian waters. It is alot smaller (60-80mm wide), more irredescent, and near impossible to see in the water, much like the box jellyfish but smaller. Other Irukandaji types include: * Fire jelly, Morbakka, Moreton Bay Stinger * Carukia Barnesi * and several undescribed carybdeis types. Commonly found in coastal Australian waters is the Cyanea jellyfish, or hair jelly/lion's mane jellyfish.
Then there are the Carybdeid species, these jellyfish usually only have a single tenticle hanging from each corner of their box shaped bodies. Species of Carybdeid including: * carybedea rastonii (jimble) * carybedea xaymacana * carybedea sivickisi * tripedalla binata Another 'stinger' that is known nation wide is the 'blue bottle'. However, most people don't know this is not actually from the same family as the other species so is technically not a jellyfish (scyphozoans & cubozoans) but they are siphonophores (hydrozoans) These 'blue bottles' are a Physalia species, another possible Physalia species is the Pacific man-o-war; it's long tenticles can be extended to ten metres long and causes a sting more painful than the blue bottle.
I believe the box jellyfish.
Australia. It's most-known for its deadly jellyfish.
Killer Jellyfish - 2005 TV is rated/received certificates of: USA:TV-PG
Yes.
Yes
Monsterquest - 2007 Killer Jellyfish 3-14 was released on: USA: 27 May 2009
Australia
The box jellyfish, which can be fatal to humans.
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In the Water.
Australia
I believe it to be the Irukandji jellyfish, found near Australia.
the box jellyfish