The Most Poisonous Animals

Brazilian Wandering Spider

The Brazilian wandering spiders appeared in Guinness 
World Records 2010 as the world's most venomous spider. Aside from causing intense pain, the venom of the spider can also cause priapism in humans. Erections resulting from the bite are uncomfortable, can last for many hours and can lead to impotence. A component of the venom is being studied for use in erectile dysfunction treatments.

The amount of P. nigriventer venom necessary to kill a 20 g mouse has been shown to be only 6 μg intravenously and 134 μg subcutaneously as compared to 110 μg and 200 μg respectively for Latrodectus mactans (Southern black widow). This ranks Phoneutria venom among the most deadly spider venoms to mice. Laboratory mice subjected to P. nigriventervenom experienced intense penile erections before succumbing to the toxin.

Inland Taipan

The Inland Taipan's venom consists of Taipoxin and protease enzymes, the average quantity of venom delivered by this species is 44 mg and the maximum dose recorded is 110 mg. The median lethal dose (LD50) for mice is 2 μg/kg (ppb) for pure Taipoxin and 30 μg/kg (ppb) for the natural venom mixture. Its venom consists mostly of neurotoxins. All reported bite victims have been treated with antivenom. As of late 2003, all positively identified inland taipan bite victims have been herpetologists handling the snakes for study, and none have been fatal.

Blue-Ringed Octopus

The blue-ringed octopus is 12 to 20 cm (5 to 8 inches), but its venom is powerful enough to kill humans. There is no blue-ringed octopus antivenom available.

The octopus produces venom that contains tetrodotoxin, 5-hydroxytryptamine, hyaluronidase, tyramine, histamine, tryptamine, octopamine,taurine, acetylcholine, and dopamine. The major neurotoxin component of blue-ringed octopus venom was originally known as maculotoxin but was later found to be identical to tetrodotoxin, a neurotoxin which is also found in pufferfish and cone snails that is 10,000 times more toxic than cyanide. Tetrodotoxin blocks sodium channels, causing motor paralysis and respiratory arrest within minutes of exposure, leading to cardiac arrest due to a lack of oxygen. The toxin is produced by bacteria in the salivary glands of the octopus.

Box Jellyfish

Box jellyfish have a square-shaped float with tentacles streaming from the corners of the bell. All box jellies can sting using nematocysts, tiny stinging cells that line the other surface of the animal. When an animal touches the box jellyfish, the nematocysts fire, puncture the victim and eject venom. The venom paralyzes and kills the box jelly’s prey, which are usually invertebrates.The venom of some box jellies can be deadly to humans as well. Of the 28 known species, only three can cause death in humans.

King Cobra

The venom of the king cobra consists primarily of neurotoxins, but it also contains cardiotoxic compounds. Toxic constituents are mainly proteins and polypeptides.

During a bite, venom is forced through the snake's half-inch (1.25 cm) fangs into the wound, and quickly attacks the victim's central nervous system, inducing severe pain, blurred vision, vertigo, drowsiness, and paralysis. Envenomation progresses to cardiovascular collapse, and the victim falls into a coma. Death soon follows due to respiratory failure.


The deathstalker is regarded as a highly dangerous species because its venom is a powerful cocktail of neurotoxins, with a low LD50. While a sting from this scorpion is extremely painful, it normally would not kill an otherwise healthy adult human. However, young children, the elderly, or infirm (such as those with a heart condition or those who are allergic) would be at much greater risk. Any envenomation runs the risk of anaphylaxis, a potentially life-threatening allergic reaction to the venom. If a sting from Leiurus quinquestriatus does prove fatal, the cause of death is usually pulmonary edema.


Its venom causes such a severe pain that the victims of its sting want the affected limb to be amputated. It is described as the worst pain known to man. It is accompanied with possible shock, paralysis, and tissue death. If not given medical attention within a couple of hours It can be fatal to humans. Stonefish stores its toxins in gruesome-looking spines that are designed to hurt would-be predators.

Poison Dart Frog

Many poison dart frogs secrete lipophilic alkaloid toxins through their skin. Alkaloids in the skin glands of poison frogs serve as a chemical defense against predation, and they are therefore able to be active alongside potential predators during the day. About 28 structural classes of alkaloids are known in poison frogs. The most toxic of poison-dart frog species is Phyllobates terribilis. It is argued that dart frogs do not synthesize their poisons, but sequester the chemicals from arthropod prey items, such as ants, centipedes and mites. This is known as the dietary hypothesis. Because of this, captive-bred animals do not contain significant levels of toxins. Despite the toxins used by some poison dart frogs, there are some predators that have developed the ability to withstand them, including the Amazon ground snake (Liophisepinephelus).


Pufferfish can be lethal if not served properly. Puffer poisoning usually results from consumption of incorrectly prepared puffer soup, fugu chiri, or occasionally from raw puffer meat,sashimi fugu. While chiri is much more likely to cause death, sashimi fugu often causes intoxication, light-headedness, and numbness of the lips, and is often eaten for this reason. Puffer's poisoning deadens the tongue and lips, and induces dizziness and vomiting, followed by numbness and prickling over the body, rapid heart rate, decreased blood pressure, and muscle paralysis. The toxin paralyzes diaphragm muscles and stops the person who has ingested it from breathing. People who live longer than 24 hours typically survive, although possibly after a coma lasting several days. Some people claim to have remained fully conscious throughout the coma, and can often recount events that occurred while they were supposedly unconscious.The paralysis reduces oxygen demands of the body dramatically, but because the toxin does not cross the blood-brain barrier, neural activity in the brain and from the eyes and ears are generally intact. In Voodoo, puffer's poison must be part of the mixture given to the victim to make them a "zombie", most likely because the paralysis and pseudo-comatose effect simulate the death portion of traditional zombie creation.

It is not believed that puffers produce toxins themselves, as puffer fish kept in tanks or fish farms are totally free of either toxin. The gastric contents of shellfish prey are believed to carry the toxins or their precursors, which are stored in the puffers organs.

Saxitoxin, the cause of paralytic shellfish poisoning and red tide can also be found in certain puffers.

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