Beauty in the natural world often comes hand-in-hand with danger. Gorgeous colours and patterns displayed by sea creatures, amphibians and insects are very often a clear warning to stay away.
Animals possess poison or venom for two main reasons: to hunt food and to defend themselves. For either purpose, the method of delivery determines whether an animal is classed as poisonous or venomous. A poisonous animal is one that has toxins in its tissue – if you touch or eat it, you will feel the effects. A venomous animal is one that actively has to bite or sting you to transfer its venom into your body. However, once the toxins are released, the chemicals pretty much do the same thing – attack vital functions in order to cause as much discomfort as possible. Many of the poisons and venoms are neurotoxins, which act on the nervous systems of mammals to cause pain or other devastating effects. Animals get their toxins by producing them within their bodies or harbouring bacteria that supply them. Alternatively, animals can gain toxins from their diet; one such critter that does this is the poison dart frog. When bred in captivity, the frogs are safe for humans to handle, as they have no contact with the foodstuffs that provide their poison. But release them back into the wild, and soon the skin of a tiny wild dart frog can contain over a milligram of the toxin – it only takes a fraction of this to kill a human.
Inland taipan: one bite could floor 100 people
Often found basking under the Australian sun in arid bushland, this snake is shy and reclusive. Professionals regard it as a placid species in contrast to its feisty relative the coastal taipan, but with one of the strongest snakebites on Earth, if it does become agitated, the results can be fatal. This snake’s venom is adapted to kill warm-blooded animals and contains an additional ‘spreading factor’ enzyme that boosts the rate of absorption. The neurotoxic venom works so quickly that the snake can bite its prey and hold on, instead of having to let go and wait before eating. The inland taipan’s venom is thought to be so potent that the amount in one bite could kill 100 humans.
Box jellyfish use sophisticated biological booby-traps
Australian box jellyfish are found in coastal waters of northern Australia and throughout the Indo-Pacific. They get their name from their cube-shaped bell and have long, trailing tentacles – the stuff of nightmares for sea swimmers. Widely regarded as one of the most venomous creatures in the ocean, the box jellyfish has adapted a potent and fast-acting toxin that it uses to instantly kill prey it comes into contact with. It delivers the dose through a series of tiny cells called nematoblasts, each of which contains a ‘nematocyst’ – a structure with a tightly-wound barb laced with lethal venom. Each of the jelly’s 15 tentacles contains 5,000 of these stinging cells. When a prey animal or unsuspecting human makes contact, the cells are triggered instantly and the wound-up barbs discharge to lodge themselves firmly into the victim’s flesh, delivering the toxin. A sting on a human can be fatal within minutes. The length of the tentacles and the method of delivery mean that a huge dose of venom can be administered in seconds. The toxin affects the heart, nervous system and skin, and victims will very often go into shock or suffer cardiac arrest. Prolonged contact with tentacles means the stinging continues, which can also eat away at the flesh and cause terrible scarring.
One king cobra bite could take down an elephant
Some animals use their poison as a last resort, but others utilise everything in their arsenal to be as terrifying as possible. The king cobra is one of the latter. When threatened or agitated, this snake can raise one third of its four-metre (13-foot) body up into the air, puff out its hood and emit a blood-curdling growl. And if that’s not enough to deter you, the king cobra will strike, using its huge fangs to administer a sinister cocktail of neurotoxins that attack the nervous system. Symptoms may include severe pain, nausea, and paralysis or coma. If untreated, this could be followed by respiratory failure and death. One fatal bite from a king cobra can channel 200 to 500 milligrams (0.01 to 0.02 ounces) of venom into its prey. Although it isn’t the most potent of venoms, a single bite contains enough toxin to kill 20 people, or even an elephant.
Blue-ringed octopuses give victims fair warning
Blue-ringed octopuses are very small and when relaxed, appear to be harmless. When a threat approaches, their iridescent blue rings flare up as a warning to stay away. If this doesn’t work, the octopuses can deliver a small bite through a tiny beak in the middle of their bodies. Its venom is contained within its saliva and transferred to the victim through the bite. The blue-ringed octopus is so small that a person may not even feel the bite, so when they begin to feel unwell, the reason is not always obvious. The mollusc’s salivary glands hold dense colonies of symbiotic bacteria that produce tetrodotoxin (TTX) – the same deadly toxin found in pufferfish – providing the octopus with plenty of ammunition for both attack and defence. TTX is a potent neurotoxin that causes muscle paralysis and leads to respiratory failure. One milligram of TTX can kill a person, making it one of the most potent toxins of the natural world, and there is no antidote.
Beware of this biting Brazilian arachnid
Found wandering the forest floors of Costa Rica, Columbia, Peru, Brazil, and Paraguay, these spiders are also infamous in the UK, after entering the country (on very rare occasions) stowed away in bunches of bananas. Brazilian wandering spiders actively avoid humans or other threats, but if the need arises and they feel in danger, they begin to warn off any would-be predators with an impressive defensive stance. If that fails, the spider will bite. The spider’s venom contains a variety of neurotoxins that attack the ion channels and chemical receptors of the nervous system. Like many other types of venom, this can cause paralysis, and in severe cases, respiratory failure. However, lethal bites are rare, as spiders won’t usually inject all of their venom, preferring to just deliver enough to deter and immobilise the threat they are facing.
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