Six Most Venomous Animals in the World

1. Box jellyfish

Often touted as the most venomous animals in the world, box jellyfish (Chironex fleckeri) cruise tropical waters around northern Australia, Papua New Guinea, Thailand, Indonesia, the Philippines and Vietnam. Each jellyfish has about 60 tentacles, each with up to 50 million nematocysts, specialised stinging cells that release like a spring when brushed. The venom leads to skin necrosis and pain so severe it can send you into shock. Death is caused by cardiovascular collapse. The exact toxins aren’t well known, but affect the heart (a cardiotoxic substance), nervous system (neurotoxic) and skin cells (dermatonecrotic) and also cause red blood cells to burst (haemolytic).

2. Funnel-web spider

Funnel-web spiders (Atrax and Hadronyche species) haunt backyards and forest regions around Australia, with some species, such as the Sydney funnel-web (Atrax robustus), having a more limited and self-explanatory geographical range. Males have more virulent venom and are more likely to attack than females (although females will if provoked) and roam outside their burrows during the spring/summer months, looking for mates.

Interestingly, the venom of funnel-webs is more toxic to primates than other mammals – despite the fact that primates aren’t their intended prey. Initial symptoms include tingling around the mouth, excessive salivating and sweating, muscle twitching and spasms which progressively worsen and lead to tachycardia (heart beating too fast) then hypotension. Antivenom is now widely available.

3. Taipan

A native Australian species found in remote, arid regions in the red centre, the inland taipan (Oxyuranus microlepidotus) and its coastal cousin (O. scutellatus) from northern Australian coasts, are two of the world’s most venomous snakes.

Their venom is a mixture of procoagulants (agents that promote blood clotting), and highly potent neurotoxins – effectively poison for nerve cells – which form the “killing molecules”, says Ken Winkel, director of the Australian Venom Research Unit at the University of Melbourne. The bite of the coastal taipan contains 50 times the median lethal dose as the king cobra and about 100 times as many as the eastern diamond rattlesnake. The neurotoxins disrupt communication between nerves, causing paralysis and subsequent death.

4. Blue-ringed octopus

The deadly blue-ringed octopus (Hapalochlaena species) dwells in tidal pools and open water across the western Pacific Ocean from Australia to Japan. Biologists originally thought the octopuses produced and stored venom in their salivary glands, but recent research has shown that the venom is produced by a bacterium that lives symbiotically within and all over the octopuses’ bodies. This bacterium is particularly concentrated in the octopuses’ tentacles. Blue-ringed octopuses can be selective in their venom administration; they have one type of venom that they use for killing their prey and another type for their own defence.

5. Brazilian wandering spider

Particularly dangerous because of its roving nature, this spider (Phoneutria nigriventer and Phoneutria fera) from tropical central and South America has ‘fangs’ – which are actually modified legs covered in red fur – that inject venom into their victims. Once injected, the victim may experience muscular paralysis leading to respiratory or cardiac arrest. As an unexpected side effect, the toxin also causes nitric oxide release, which can cause priapism – an involuntary erection “so hard you can charge it through a brick wall,” says biochemist Bryan Fry of the University of Queensland in Brisbane.

6.Golden poison dart frog

The golden poison dart frog (Phyllobates terribilis) lives in the rainforest on the Colombian coast. Their extremely potent toxin is transferred via their skin, secreted by glands behind the frog’s ears. Some scientists believe that the frogs sequester their venom through their diet, as frogs kept in captivity lose toxicity. Called batrachotoxin, the active component primarily affects the heart causing arrhythmias, fibrillations and eventually cardiac arrest. It also increases sodium permeability, which amplifies communication in the nervous system, putting it into overdrive.

via World’s most venomous animals

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4 Responses to Six Most Venomous Animals in the World

  1. alfy says:

    We know why jellyfish have nematocysts, (to paralyse the small fish they prey on for food). The curious will wonder why the box jellyfish have evolved venom which is quite so spiteful. It would appear to be overkill and natural selection usually does not favour excessive responses as they are not economical of resources. Have any biologists offered explanations of the extreme toxicity? May be the jellyfish eat killer whales.

  2. Deskarati says:

    Well I couldn’t find any further information as to why the Box Jellyfish or ‘Sea Wasp’, as it is more commonly known, is so venomous. But I don’t think the killer whale will be losing any sleep.
    Happy New Year, Alfy.

  3. alfy says:

    Thank you for looking for an answer to the puzzle, Jim.

  4. Phil Krause says:

    Box jellyfish must have evolved their extremely toxic venom by natural selection. Probably the places to look first are the animals that it preys on and the animals that prey on it as the most successful would be the ones best able to feed themselves and survive their predators. They seem to eat quite a lot of shrimps amongst other things. Box jellyfish are generally much smaller than other species and would be damaged considerably more from a thrashing shrimp trying to escape after it had been stung. Therefore the ones who’s venom killed the shrimps the quickest would receive the least damage from them before they died. They now seem able to kill shrimp almost instantly but a consequence of this is that Australians and tourists are forced to wear stinger suits while swimming in the sea around north Queensland and other places where they live.
    Looking at the other end, they are preyed on by turtles that don’t seem to be effected by their venom. Maybe that they were just lucky being naturally immune to their stings, but more likely they have evolved to be more and more resistant over time.
    Even more interestingly, the box jellyfish is able to see through four eyes, one at the centre of each side of the bell. They do seem to avoid, even the tiniest of objects and probably try to avoid humans as well but we swim into them quicker than they can escape and bump into their tentacles. Other jellyfish also have primitive eyes but it is thought that they can only detect the difference between light and dark where as the box jellyfish seem to take avoiding actions just like they can see small objects. Why is this a puzzle, I hear you ask? Well its a puzzle because they are not thought to have a brain.

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