Marbled Cone snail
This little beautiful looking Marbled Cone snail can be as deadly as any other animal on this list. One drop of its venom is so powerful that it can kill more than 20 humans. If you ever happen to be in warm salt water environment (where these snails are often found) and see it, dont even think of picking it up. Of course, the true purpose of its venom is to catch its prey. Symptoms of a cone snail sting can start immediately or can be delayed in onset for days. It results in intense pain, swelling, numbness and tingling. Severe cases involve muscle paralysis, vision changes and breathing failure. There is no antivenom. However, only about 30 human deaths have been recorded from cone snail envenomation.