7. Irukandji jellyfish
Source: Iconosquare
More commonly known as the Box Jellyfish, this innocent looking jellyfish may be the deadliest creature in Australia. It possesses a venom that is 100 times more potent than a cobra’s. The sting causes acute pain and is psychoactive- causing anxiety in its victims. The venom attacks the central nervous and cardiac systems. This creature inhabits the northern half of the Australian coastline and can grow up to four & ½ meters in length.