#5 – Blue Ringed Octopus
The size of the Blue Ringed Octopus is very small like a golf ball. Its venom is so powerful that it can kill around 20 adult humans within minutes. The bite of this Octopus may feel painless but its neurotoxins paralyze the breathing and movement muscles. Its venom can cause nausea, heart failure, sometimes paralysis and blindness as well and if not treated quickly, can lead to a nasty death.