الحيوان الأكثر سماً على وجه الأرض.. لمسة واحدة تجمد أعصابك

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By Sumitra on April 1st, 2016 Category: Animals

The golden poison dart frog is a very deceptive creature – despite its tiny two-inch frame, it happens to be the most poisonous creature on Earth. A single amphibian packs enough venom in it to kill over 10 adult men in about 3 minutes. In fact, the species gets its name from the native Emberá hunters of Colombia, who once used the frogs to make lethal blowgun darts.

The bright yellow frogs can only be found in small rainforest on the Pacific coast of Colombia, and their coloring can sometimes vary between yellow, orange, or pale green. The glamour of their appearance is a deliberate ploy, a tactic called aposematic or ‘warning’ coloration, to ward off potential predators. As proven by a 2001 study by Kyle Summers of East Carolina University in Greenville, the brightest frogs are always the most toxic.

Simply coming in contact with a golden poison dart frog doesn’t necessarily put you in mortal dangers, as the amphibians only produce and excrete the potent toxin through their skin only when they feel threatened. But picking up one of these tiny creatures and holding it in your hand for more than a few seconds without gloves is suicide. The frog’s skin quickly becomes covered in alkaloid poison (batrachotoxin) that has the ability to ‘freeze’ nerves, stopping them from transmitting impulses. Within minutes, the victim experiences uncontrollable muscle contractions and eventually heart failure.

Photo: Wilfried Berns

Scientists have not been able to determine the exact reason behind the frog’s extreme toxicity. They have traced its origins back 40 to 45 million years, in the forests of northern South America, and found that their ancestors were not poisonous.There is some speculation that the creatures did not generate their own poison, but ingested huge amounts of plant poisons, mainly carried by their prey – flies, toxic ants, crickets, beetles, and termites. Their high metabolic rate could have allowed them to process the venom rather quickly, allowing them to withstand and even absorb it. This theory is further strengthened by the fact that poison dart frogs that are raised in captivity never develop any venom.

Interestingly, a 2014 study by Ralph Saporito of John Carroll University, Ohio, found that tiny tadpoles receive venom from their poison dart mothers, through a feed consisting of unfertilized eggs. The babies absorb venom through the feed and become poisonous themselves. “Mom is able to provide them a defence by placing alkaloids in the eggs,” Saporito explained. “It appears that the alkaloids in tadpoles are sufficient in deterring some potential arthropod predators such as hungry dragonflies.” Their bright color, of course, stops predators from attacking in the first place.

Photo: Marcel Burkhard

Sadly, the magnificent golden poison dart frogs are an endangered species due to the widespread destruction of their natural rainforest habitat through deforestation, and illegal gold mining, cocoa cultivation, and logging. “Astonishing: we are on the edge of wiping out one of the most extraordinary and thrilling creatures on the planet,” journalist Simon Barnes wrote in 2011. “We would all be much poorer without such a creature to give us nightmares.”

To protect the species, international conservation charity World Land Trust set up the Rana Terribilis Amphibian Reserve in the wettest tropical rainforests of western Colombia. According the organisation’s website, “Living in the rich undergrowth of the reserve is a healthy population of Endangered Golden Poison Frog, one of the most extraordinary creatures on the planet. Just 55mm in size, this tiny vibrant creature carries a single milligram of toxin – a small but lethal dose.”

Photo: The Lord of the Allosaurs

The website goes on to explain that  the Emberá Indians learned how to use this poison to their advantage by gently brushing the tips of their arrows and darts on a frog’s back without hurting it. Weapons prepared in this manner would remain deadly for over two years.

A BBC account, however, describes a more gruesome process of venom extraction from the poison dart frogs, which keeps its poison in glands beneath its skin. “Local people would ‘catch frogs in the woods, and confine them in a hollow cane.’ When they needed poison, they would take a frog and ‘pass a pointed piece of wood down its throat, and out at one of his legs.’ Unsurprisingly, the frog would become agitated, and begin sweating poison, ‘especially on the back, which becomes covered with white froth.’ The people dipped their arrows in this poisonous liquid, which remained potent for a year.”

Photo: Micha L. Rieser

Currently, medical researchers and amphibian experts are interested in discovering possible medicinal uses to the poison dart frog’s venom, especially as painkillers. “It’s not that the compounds cause toxic effects that is of interest here,” explained Richard Fitch of Indiana State University, speaking to the BBC. “It’s the way they do it that is useful to the scientist and physician. In the past, alkaloids have been found to possess cancer-fighting and pain numbing properties, and stimulants as potent as caffeine. Of course, the venom cannot directly be administered as medicine, but understanding its structure and chemistry could help design better drugs.

“If we can cut the key just right, we get the activity we want,” Fitch said. “That’s perhaps a tall order, as we don’t quite know what the bus looks like, but we have a key and that’s a start.”

Sources: BBC, National Geographic, World Land Trust