My Science School

Chytridiomycosis

Chytridiomycosis is an infectious disease that affects amphibians worldwide. It is caused by the chytrid fungus (Batrachochytrium dendrobatidis), leading to deaths in frogs, toads and salamanders. A report released in 2019 revealed that it has caused declines in at least 501 frog and salamander species in the last 50 years.

Of these, some 90 species are presumably extinct in the wild and 124 are suffering serve declines due to the disease, the report said. In many species, the fungus is the main factor in the deaths, but in others, it’s a combination of the disease and other factors such as habitat loss, climate change and predation from invasive species.

Chytrid fungi that infect vertebrate species live in water or soil. They reproduce asexually and have spores that swim in the water. Amphibians contract the disease when their skin comes in contact with water containing spores or with other affected amphibians. The fungus affects their skin, making it difficult for them to breathe (amphibians use their skin for respiration). The fungus also damages the nervous system, affecting their behaviour. It doesn’t kill the amphibians immediately, which increases the odds of the pathogen spreading rapidly.

The disease is thought to have spread around the world via the pet and meat trade.

Chytridiomycosis has affected amphibian populations in more than 60 countries, with the largest die-offs in Australia, Central America and South America.

Devil Facial Tumour Disease

The Tasmanian devil, a marsupial native of Australia, has suffered a dramatic population decline due to Devil Facial Turmour Disease (DFTD). First discovered in northeastern Tasmania in 1996, the disease has since spread across 95% of the species’ range. Up to 90% of their populations have been wiped out.

The disease is spread through biting during fighting or mating. It spreads particularly when canine teeth come into contact with the diseased cells. The rough cells then settle down in their new host, developing into tumours on face, neck and other parts of the body. The devils soon find it difficult to eat and drink, and usually die from starvation and dehydration. The cancer also affects other bodily functions such as respiration and blood circulation. An infected devil dies within six months. According to some predictions, DFTD could wipe out wild Tasmanian devils in less than 40 years.

White-Nose Syndrome

White-Nose Syndrome (WNS) is a fungal disease that has killed over six million bats in North America in over a decade. Caused by the fungus Pseudogymnoascus destructans, or Pd, the disease has spread to 33 U.S. States and seven Canadian provinces. Some populations have declined by more than 90 % within five years of the disease reaching a site. As of 2017, 15 bat species have been affected by WNS.

The fungus infects the skin on the nose, mouth,ears and wings of hibernating bats. The fungus thrives in cold and humid environments such as caves and mines used by bats. Bats can catch the fungus from physical contact with infected bats. The signs observed in bats with WNS include unusual winter behaviour-they experience frequent arousal from sleep and instead of continuing with the hibernation, the bats fly far out of their caves, even in daylight. As a result they quickly drain their fat reserves, and starve to death, Infected bats also show evidence of blood acidification and dehydration.

Sea Star Wasting Syndrome

Sea Star Wasting Syndrome (SSWS) has been linked to the mass die-offs of starfish and several other echinoderms (such as sea urchins, sand dollars and sea cucumbers) since 2013 in the Pacific waters from Mexico to Alaska. In 2014, it was suggested that the disease is caused by densovirus; but subsequent work revealed that an association between a viral pathogen and SSWS was unlikely.

The symptoms begin with white lesions on their limbs, decay of tissue surrounding the lesions and loss of limbs. The sea star would eventually turn into a mushy blob and die. Forty species of sea stars have been affected by this disease.

Research has shown that warming ocean temperatures could play a role in exacerbating the disease. But the actual causative agent for SSWS remains elusive.

Hemorrhagic Septicemia

One day in May 2015, a handful of saiga antelops were found dead in the steppe of Kazakhstan. The next day saw more deaths. Within three weeks, some 2,00,000 – 62% of the world’s population – were dead. This alarmed the scientists from across the globe as the species was already critically endangered in Central Asia. The reported symptoms were foaming at the mouth, diarrhoea and bloating. Initial research revealed it could be due to a disease. A 2018 report confirmed that the killar was a bacterium, Pasteurella multocida, that normally lives in the antelopes’ tonsils without causing any problems. It also revealed that unusually warm, moist weather may have triggered the overgrowth of the bacteria, which subsequently found its way into the antelopes’ tissues and bloodstream, causing haemorrhagic septicaemia or  fatal blood poisoning. Researchers say there is a high chance of the same thing happening again, given the climate change predictions for the region.

Similar die-offs were reported in 2010 and 1988. They were also linked to Pasteurella multocida. Today, roughly 50,000 saigas are thought to remain in the wild, according to the World Wildlife Fund.

 

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Cheetahs have two tear lines that run from the inside corners of their eyes down to the outside edges of their mouth. These marks help reflect the sun’s glare whenever the cats are off hunting during the sunniest of days – in that way, cheetahs don’t get blinded by direct sunlight like we do, even in midday.

The tear lines work in a similar way to the black marks worn by rugby players. They’re also helpful features for the cheetah in order to stay focused on its prey.

There is a Zulu folklore tale about how the cheetah got its tear lines: once, a hunter was too lazy to be about his business, wishing that someone could get the meat for him. Soon, he saw a female cheetah making a successful kill and feeding it to her cubs, and all of a sudden decided to steal all these cubs in order to train them for hunting.

Soon, when the mother cheetah was away, the wicked hunter accomplished his terrible deed, kidnapping all the cubs without leaving a single one. Once the mother found her babies gone, she became heartbroken, searched for them far and wide, and kept calling and crying all day and night, so long and so hard, until her tears made dark stains down her cheeks.

Soon, the elders got wind of the event and went to punish the lazy hunter, who had also broken the tribe’s most sacred traditions – in Zulu culture, it’s tradition that a hunter must use only his own strength and skill, otherwise dishonor comes. But even when the wicked man was eventually forced to bring the cubs back to their mother, nevertheless her long weeping stained her face forever – and those tears are worn by her children (modern-day cheetahs) to this day.

According to the locals, this tale carries a moral: a cheetah wearing the tear stains on its face is a reminder for hunters that it is not honorable to hunt in a non-traditional, inconvenient way.

 

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Thus, when they see an open safari vehicle, full of people, all they see is one single thing: a large beast with some appendices on top (heads). As a large, and potentially powerful, beast does not interest them, as well as other large animals such as adult rhinos and elephants: they know the hunting effort is not worthy. Not because they fear humans.

However, all attention is necessary, as apex predators such as lions or even leopards are relatively intelligent and curious animals. If somebody stands up and detaches himself from the rest of the “beast mass”, the predator may be curious and in doubt if that is a part of the large beast or is something else separate: it may then investigate or attack. In case of an attack, we all can imagine what happens. If it starts to investigate too close, many tourists may lose their nerve, stand up and even run… which will be the worst mistake, as the predator will then be sure that it is a prey and will start chasing (hunting reflex), and they run much faster than any of us.

Considering that, the local guides normally orient passengers to stay seated, quiet, only observing when close to animals. They teach you to never stand up, shake arms or worst, get out of the safari vehicle. In this last case, the animal will be sure you are not part of the large beast and will notice you are actually the perfect size for a prey…

However, some private game reserves do not disclose the fact that, in order to maintain the “savage aspect” of the tour, especially those where an open safari vehicle is used, they “prepare” the animals to get used to human presence. Before opening a new game reserve or when new animals are bought (yes, they do buy animals from other places to populate or replace losses, so there is plenty to be seen by tourists), they get the animals used to the safari vehicle and people, by running close to them on a frequent basis, until the animal is used to the vehicle and people and do not show aggressiveness anymore. They do it until the “large beast” is already a part of the landscape. That is why they really do not attack.

Nevertheless, if a pack of lions insist on being aggressive to humans, which makes the reserve lose money, they resell or even shoot down the rebels. Sad, no? No publicity on this, bad for business.

 

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While many animals in the world look dangerous and live up to their frightening appearances, there are many others which pose little to no threat to us humans.

Here’s my list of 7 scary looking animals that are practically harmless.

1. Gharial

Many people would be right to fear a gharial if they’ve heard stories about how other crocodilians kill hundreds of humans each year, but is this slim snouted creature really as dangerous as its cousins?

In truth, gharials only hunt small prey like fish and frogs as their jaws are too slim and weak to take down larger quarry. As a result gharials are unable to attack large prey, namely humans.

2. Milk snake

While, the milk snake may bear a striking resemblance to the venomous coral snake they are completely harmless. They have no venom and are actually quite docile in nature which makes them pretty good pets for reptile lovers.

3. Sand tiger shark

Most people know that sharks in general don’t deserve their fearsome reputation as an eating monsters but very few of them are completely harmless. While, the great white, tiger and bull shark have all been known to kill people, the sand tiger shark is actually completely harmless.

This shark’s barbed jaws may look threatening but these scary looking teeth are exactly what keep this fish from being even a slight danger towards us. The shark’s mouth is too small to cause a human fatality so only squid and fish fall victim to this shark’s jaws. While this shark is very docile there have been a few attacks when it’s been provoked…

4. Goliath bird eater

Goliath bird eating spiders may have venom. They may take down small birds and they may be freaking massive but are they really a danger towards humans?

In truth this tarantula’s venom is harmless and is quite similar to how a wasp’s sting would feel. Main difference is that these spiders only bite in self defense, so I’m pretty sure you won’t be bothered by this giant.

5. Manta rays

Manta rays are very large and if you have ever heard of sting rays, you might be frightened by this aquatic creature. Manta rays are actually gentle giants and are only filter feeders, meaning they eat really small prey. To make things better, they don’t have stingers so divers have nothing to fear!

6. Thorny devil

These lizards may be small but I’m pretty sure most of us would be scared if this spiky reptile came charging. Luckily this animal only feeds on insects and when it does feel threatened it squirts blood from its eyes…which may seem gross but wouldn’t really harm a human being. To make things even better, these scary looking lizards run at the first sight of a human being!

7. Basking shark

The second-largest shark species is pretty harmless despite its frightening set of jaws. Like many of the ocean’s largest predators, this creature is a filter feeder and that means humans aren’t on the menu!

 

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It's because Lions and Tigers do not co-exist in a shared territory anymore (thanks to humans).

However Tigers and Lions used to share common habitats in Asia, specially India and Iran before the end of 20th century. Fights between these two beasts were recorded in the accounts of travellers, folklore and stories.

20th Century had been the worst century for animals in these regions. Both British and Indian/Persian Royals hunted down Tigers and Lions in huge numbers, bounty was put on them and due to rapid urbanization and huge agricultural demands their habitats were run over by human occupation.

Lions were less of a shy animal compared to Tigers which preferred to hide in deep forests, so Lions were killed more, so much so that Lions went locally extinct in Iran and most of India.

Only 12 were left in a small forest in Gujarat, India by the end of 20th Century. They were able to survive because King of that region decided to protect them.

Tigers also perished as they were also hunted down to near extinction.

They became extinct in Iran and were only able to survive in small pockets of forests in India.

So, if not so for relentless hunting of Wild Animals by humans in 20th Century, Tigers and Lions would had still co-existed with each other in Jungles of Persia and India, and we may had witnessed Tigers and Lions fighting over territory and prey in the wild itself.

 

Credit : Quora

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