5. Blue Ringed Octopus
This is a very small animal, about the size of a golf ball. Do not underestimate it because of its size, it holds enough venom to kill 26 fully grown adults and unfortunately, there is no antidote. To make matters worse, its bite is usually painless; you will only become aware of it when the deadly neurotoxins begin to work, which is almost immediately.
If you ever get bitten by this animal, you will be paralyzed within minutes and unable to breathe at the same time.
Assuming you receive artificial respiration, the toxin will show you no mercy as you will remain conscious until the venom is neutralized by your body.