Jellyfish, also known as sea jellies, are the medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria.
The Scyphozoa are an exclusively marine class of the phylum Cnidaria, referred to as the true jellyfish.
Box jellyfish are cnidarian invertebrates distinguished by their box-like body. Some species of box jellyfish produce potent venom delivered by contact with their tentacles. Stings from some species, including Chironex fleckeri, Carukia barnesi, Malo kingi, and a few others, are extremely painful and often fatal to humans.
Rhopalia from Ancient Greek ῥόπαλον (rhópalon) 'club' are small sensory structures of certain Scyphozoan and Cubozoan species.
The Irukandji jellyfish are any of several similar, extremely venomous species of rare jellyfish. With a very small adult size of about a cubic centimetre, they are both the smallest and one of the most venomous jellyfish in the world. They inhabit the northern marine waters of Australia, and cost the Australian government $AUD 3 billion annually through medical costs associated with stings and tourism losses. This type of jellyfish reproduces sexually with eggs and sperm. They fire their stingers into their victim, causing a condition known in humans as Irukandji syndrome, which can be fatal and difficult to immediately recognise due to the delayed effects of the venom. There are about 16 known species of Irukandji, of which Carukia barnesi, Malo kingi, Malo maxima, Malo filipina and Malo bella are the best known.
Discomedusae is a subclass of jellyfish in the class Scyphozoa. It is the sister taxon of Coronamedusae. Discomedusae contains about 155 named species and there are likely to be many more as yet undescribed. Jellyfish in this subclass are much more likely to have swarming events or form blooms than those in Coronamedusae. Discomedusae consists of two orders, Rhizostomeae and Semaeostomeae.
Alatina alata(Reynaud, 1830), often called a sea wasp, is a species of box jellyfish found in the Pacific, Indian and Atlantic Oceans and in the Caribbean and Arabian Sea.
Malo kingi or the common kingslayer is a species of Irukandji jellyfish. It was first described to science in 2007, and is one of four species in the genus Malo. It has one of the world's most potent venoms, even though it is no bigger than a human thumbnail. As an Irukandji, it can cause Irukandji syndrome, characterized by severe pain, vomiting, and rapid rise in blood pressure.
Euglossa bazinga is a euglossine bee species found in Brazil. It is named after the catchphrase of the fictional character Dr. Sheldon Cooper from the television show The Big Bang Theory. It was previously misidentified as Euglossa ignita, and is threatened with habitat loss.
Bazinga is a genus of rhizostome jellyfish with only one known species, Bazinga rieki, found off the central eastern coast of Australia.
Carybdea murrayana, the South African box jellyfish, is a venomous species of cnidarian, in the small family Carybdeidae within the class Cubozoa.
Copula is a monotypic genus of box jellyfish in the family Tripedaliidae of the phylum Cnidaria. The only species in the genus is Copula sivickisi, a very small gelatinous, bell-shaped jellyfish with four tentacles that is active only at night. It is unusual among box jellyfish in having a mating ritual and internal fertilization. Its scientific name honours the Lithuanian zoologist Pranciškus Baltrus Šivickis.
Lisa-ann Gershwin, also known as Lisa Gershwin, is a biologist based in Launceston, Tasmania, who has described over 200 species of jellyfish, and written and co-authored several non-fiction books about Cnidaria including Stung! (2013) and Jellyfish – A Natural History (2016). She provides independent advice related to jellyfish worldwide to the media, online and via The Jellyfish App. She was an unsuccessful candidate in the 2021 Tasmanian state election running as an independent in the electorate of Clark.
Chirodectes is a very rare, monospecific genus of box jellyfish in the family Chirodropidae.
The thimble jellyfish is a species of cnidarian found in the warm West Atlantic Ocean, including the Caribbean. It is a tiny jellyfish with a straight-sided, flat-topped bell. This jellyfish is the most common cause of seabather's eruption, a reaction caused by the injection of juvenile jellyfish nematocysts into human skin.
Poralia is a genus of jellyfish in the family Ulmaridae. It is a monotypic genus containing a single species, Poralia rufescens. This jellyfish is pelagic, and is found in deep water in most of the world's oceans.
Chiropsella bronzie is a species of box jellyfish. It is considered much less of a threat to humans than some of its relatives. The species was described in 2006, and is one of four species in the genus Chiropsella. Chiropsella bronzie can be found in shallow waters off the coast of Queensland, Australia.
Crambionella is a genus of Cnidarians belonging to the family Catostylidae. The genus is distinguishable from other Castostylid species by a terminal club on each oral arm without filaments and a canal system featuring a narrow, wide-meshed intra-circular network of interconnected vessels. These vessels solely communicate with the ring canal and not with the radial canals. Four species belong to the genus Crambionella : C. annandalei, C. helmbiru, C. orsini and C. stuhlmanni. C. orsini is the type species for the genus.
Stomolophus fritillarius is a species of true jellyfish in the family Stomolophidae. It is on occasion, collectively with Stomolophus meleagris, referred to as the cannonball jellyfish.
Atorella octogonos is a species of crown jellyfish in the family Atorellidae. It has been found in the Bahamas.
