Jellyfish several countries; jellyfish caused a cascading blackout in the Philippines in 1999, as well as damaging the Diablo Canyon Power Plant in California in 2008. They can stop desalination plants and ships' engines. Jellyfish Jellyfish or sea jellies are the informal common names given to the medusa-phase of certain gelatinous members of the subphylum Medusozoa, a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animals with umbrella-shaped bells and trailing tentacles, although a few are not mobile, being anchored to the seabed by stalks. The bell can pulsate to provide propulsion and highly efficient locomotion. The tentacles
Irukandji jellyfish by Hugo Flecker in 1952. They were named after the Irukandji people, whose country stretches along the coastal strip north of Cairns, Queensland. The first of these jellyfish, "Carukia barnesi", was identified in 1964 by Jack Barnes; to prove it was the cause of Irukandji syndrome, he captured the tiny jelly and allowed it to sting him, while his 9-year-old son and a lifeguard observed the symptoms (and then rushed him to ICU). Australian toxinologist Jamie Seymour made a documentary about the jellyfish called 'Killer Jellyfish'. In 2015, North Queensland researchers discovered evidence that Irukandji jellyfish actively hunt prey. The