The Irukandji jellyfish (/ɪrəˈkændʒi/ irr-ə-KAN-jee) are any of several similar, extremely venomous species of rare jellyfish. With a very small adult size of about a cubic centimetre (1 cm3), they are both the smallest and one of the most venomous jellyfish in the world. They inhabit the northern marine waters of Australia. They fire their stingers into their victim, causing a condition known in humans as Irukandji syndrome, which can be fatal. 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.
Irukandji jellyfish

