Category extinction

What is a real life example of extinction?

We are in the middle of a mass extinction brought about by human activity.

What is mass extinction?                       

A vast number of species going extinct at one period in time is called mass extinction. It is also known as a biotic crisis, as it leads to a decline in the world’s biodiversity. In a mass extinction, species disappear faster than they are replaced by new species.

What are the causes of mass extinction?

Earlier extinctions took place due to natural causes like global climate change, fluctuating sea levels and catastrophic events like volcanic eruptions or asteroid impacts. However, the ongoing extinction is the result of human actions.

How many mass extinction events have occurred on the Earth?

The Ordovician-Silurian extinction, 444 million year ago; the Devonian extinction, 360 million years ago; the  Permian extinction, 250 million years ago; the Triassic-Jurassic extinction, 201 million years ago; and the Cretaceous extinction, 65 million years ago. The first eliminated marine invertebrates, the second, tropical marine species. The third and the largest decimated most of the marine species and many terrestrial vertebrates, and the fourth destroyed all the Triassic reptiles. The fifth last was most likely caused by an asteroid hitting the Earth. It killed off dinosaurs of all species, including the remaining non-avian dinosaurs.

Are we facing a sixth mass extinction?

At present, we are in the middle of the sixth mass extinction, the Holocene extinction, which is entirely caused by the humans. It started 10,000 years ago with the beginning of agriculture and industrialization. Human activities like deforestation, climate change, and pollution have been major contributors.

These events wipe out numerous species, reshaping ecosystems and allowing the evolution of new species. They can disrupt habitats, biodiversity, ecological stru and food chains.

What is the impact of mass extinctions?

These events wipe out numerous species, reshaping ecosystems and allowing the evolution of new species. They can disrupt habitats, biodiversity, ecological structure and food chains.

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Why are anteaters going extinct?

As their name suggests, giant anteaters are large. Like so many large mammals the world over, these creatures too are facing rising extinction risk, especially in Brazil. What are the reasons for this? Come, let’s find out.

Giant anteaters are native to Central and South America. In 2020, the Pantanal region of South America witnessed fires that destroyed about a third of the area. It proved to be injurious or fatal for wildlife such as jaguars inhabiting the region. According to a report, the fires killed “an estimated 17 million animals”. The numbers are not available for those injured or displaced. But among those that suffered are giant anteaters. Apparently, “more than 50 giant anteaters injured or displaced by the Pantanal fires were taken in by state rescue projects – a leap from 13 the previous year”. In 2021, Pantanal witnessed fires again, though on a scale smaller than the previous year. However, reports suggest that a few areas from 2020 suffered in 2021 too – this could spell disaster for the species there since they’d be denied time for recovery. Several animals are also indirectly affected by such fires. For instance, young animals could be orphaned and ones trying to escape such fires could get involved in accidents or end up in the hands of poachers. As for giant anteaters, some tried to escape the fire in 2021 and got hit by cars; they were rescued.

But, fires are not the only reason for falling giant anteater populations. A report says “Brazil’s anteater populations have fallen 30% over 26 years”. As solitary creatures, they require a large range for habitation. But this is becoming more and more difficult due to land seizures, expansion of farming, ranching, and mining “in the Amazon and the Brazilian savanna”. Further, the animal also has “a low population growth rate due to its life history of long gestation periods and single offspring”.

The giant anteater plays a significant role as both predator and prey. While it is consumed by jaguars and pumas, the mammal consumes large quantities of insects, especially ants and termites. Given this interconnectedness, the extinction of this insectivore can have unimaginable impacts on its ecological range.

Fires are not the only reason for falling giant anteater populations. As solitary creatures, they require a large range for habitation. But this is becoming more and more difficult due to land seizures, expansion of farming, ranching, and mining “in the Amazon and the Brazilian savanna”. Further, the animal also has “a low population growth rate due to its life history of long gestation periods and single offspring”.

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Is our world undergoing the sixth mass extinction?

There’s proof we are increasingly losing species, and this is not good for us humans

What is mass extinction?

To be classified as a mass extinction, at least 75 % of all the species on Earth must go extinct within a short geological period of less than 2.8 million years. That timeframe seems long to us because modern humans have only existed for about 2,00,000 years so far.

Mass extinction is not new

Extinctions and speciations (species evolving over time) do not happen at uniform rates through time; instead, they tend to occur in large pulses interspersed by long periods of relative stability. These extinction pulses are what scientists refer to as mass extinction events. The Cambrian explosion was a burst of speciation some 540 million years ago. Since then, at least five mass extinction events have been identified in the fossil record (and probably scores of smaller ones). Arguably the most infamous of these was when a giant asteroid smashed into Earth about 66 million years ago in what is now the Gulf of Mexico. The collision vapourised species immediately within the blast zone. Species were killed off later by resultant climate change and volcanic activity too.

Are humans responsible for the current crisis?

Humans have been implicated in smaller extinction events going back to the late Pleistocene (around 50,000 years ago) to the early Holocene (around 12.000 years ago) when most of the megafauna, such as woolly mammoths, giant sloths. diprotodons, and cave bears, disappeared from nearly every continent over a few thousand years. Much later, the expansion of European colonists throughout the world from about the 14th Century precipitated an extinction cascade first on islands, and then to areas of continental mainland as the drive to exploit natural resources accelerated. Over the last 500 hundred years, there have been more than 700 documented extinctions of vertebrates and 600 plant species. These extinctions come nowhere near the 75 % threshold to include the modern era among the previous mass-extinction events. But those are just the extinctions humans have recorded. In fact. many species go extinct before they are even discovered- perhaps as many as 25 % of total extinctions are never noticed by humans. But it’s not the total number of extinctions we should focus on; rather, it’s the extinction rate. Even the most conservative estimates place the modern era well within the expected range to qualify as a mass extinction. If the current rate of extinction continues we could lose most species by 2200.

When species disappear

One may think that so long as the species that provide resources for modern societies survive, there’s no reason to consider extinction a problem. The evidence suggests otherwise. Species loss also erodes the services biodiversity provides us. These include reduced carbon removal from atmosphere (which climate change), reduced pollination and increased soil degradation that compromise our food production, poorer water and air quality, more frequent and intense flooding and fires, and poorer human health. Even human diseases such as HIV/ AIDS, Ebola, and COVID-19 are the result of our collective indifference to the integrity of natural ecosystems.

There’s still hope

We could potentially limit the damage if societies around the globe embraced certain fundamental, yet achievable, changes. We could abolish the goal of continuous economic growth, and force companies to restore the environment. We could limit undue corporate influence on political decision-making. Educating and empowering women would also help stem environmental destruction.

Did you know?

  • In the timeline of fossil evidence going right back to the first inkling of any life on Earth- over 3.5 billion years ago – almost 99 % of all species that have ever existed are now extinct. That means that as species evolve over time, they replace other species that go extinct.
  • When the giant asteroid hit our planet, about 76 % of all species around at the time went extinct, of which the disappearance of the dinosaurs is most well-known. But dinosaurs didn’t disappear altogether-the survivors just evolved into birds.

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Do penguins face threat of extinction?

As much as 98% of colonies of this penguin species is at risk of extinction by 2100. So, the U.S. has listed the bird as “threatened” under the Endangered Species Act. There’s still hope to save them.

Where do emperor penguins live?

Different species of penguins are found in different parts of the Southern Hemisphere. The emperor penguins are found only in Antarctica, where they live and breed. Emperor penguins thrive on Antarctica’s coastlines in icy conditions any human would find extreme. The penguins breed on fast ice, which is sea ice attached to land But they hunt for food within the pack ice-sea ice floes that move with the wind or ocean currents and may merge. Sea ice is also important for resting, during their annual moult, and to escape from predators.  

The U.S. lists them as “threatened”.

If current global warming trends and government policies continue, Antarctica’s sea ice will decline at a rate that would dramatically reduce emperor penguin numbers to the point that 98% of all their colonies would become quasi-extinct by 2100, with little chance of recovering, a new study has shown. That’s why the U.S. Fish and Wildlife Service finalised a rule listing the emperor penguin as “threatened” under the Endangered Species Act, effective November 25, 2022. The director of the service said the listing “reflects the growing extinction crisis”. The U.S. Endangered Species Act has been used before to protect other species that are primarily at risk from climate change, including the polar bear, ringed seal, and several species of coral, which are all listed as threatened.

But, these penguins don’t even live in the U.S.!

Sure, these penguins don’t live on US. territory, so some of the Endangered Species Act’s measures meant to protect species habitats and prevent hunting them don’t directly apply. Being listed under the Endangered Species Act could still bring benefits, though. It could provide a way to reduce harm from U.S. fishing fleets that might operate in the region. And, with expected actions from the current administration, the listing could eventually pressure U.S. agencies to take actions to limit greenhouse gas emissions. However, the Bureau of Land Management has never acknowledged that emissions from oil and gas extraction on public lands and waters could harm climate-imperiled species. It issued more than 3.500 oil and gas drilling permits in New Mexico and Wyoming on public land during the first 16 months of the Joe Biden administration.

What’s harming the birds?

The greatest threat emperor penguins face is climate change. It will disrupt the sea ice cover they rely on unless governments adopt policies that reduce the greenhouse gases driving global warming. If there’s too much sea ice, trips to bring food from the ocean become long and arduous, and their chicks may starve. With too little sea ice, the chicks are at risk of drowning. Climate change is now putting that delicate balance and potentially the entire species at risk. Emperor penguins are adapted to their current environment, but the species has not evolved to survive the rapid effects of climate change that threaten to reshape its world. Major environmental shifts, such as the late formation and early loss of sea ice on which colonies are located, are already raising the risk.

How can we save them?

Decades of data since the 1960s are now helping scientists gauge the effects of anthropogenic climate change on the penguins, their sea ice habitat and their food sources. Meeting the Paris Agreement goal could still save the penguins. The results of the new study showed that if the world meets the Paris climate agreement targets, keeping warming to under 1.5 degrees Celsius (2.7 F) compared with pre-industrial temperatures, it could protect sufficient habitat to halt the emperor penguins decline. But the world isn’t on track to meet the Paris Agreement goals. The future of emperor penguins, and much of life on Earth, including humanity, ultimately depends upon the decisions made today.

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Why are dugongs extinct in China?

A gentle giant, the dugong is functionally extinct in China. Dugong, a gentle marine mammal related to the manatees that lived in China’s southern waters for hundreds of years, has been declared functionally extinct – so few in number that it cannot recover – in the country.

Weighing almost half a tonne, the ocean’s most gentle giant is the only vegetarian marine mammal. Its diet consists mostly of seagrass. Despite having an appearance similar to the manatee, it is different due to its dolphin fluke-like tail and gentle disposition. Some people believe that it inspired ancient tales of mermaids and sirens.

Commonly known as “sea cows”, dugongs are usually found in the coastal waters from East Africa to Vanuatu and even Japan. They are found in 37 more tropical regions in the world, especially in the shallow coastal waters of the Indian and western Pacific Oceans.

The creature is listed as vulnerable in the International Union for Conservation of Nature Red List.

According to research by the Zoological Society of London and the Chinese Academy of Sciences, fishing, ship strikes, and human-caused habitat loss have resulted in the rapid decrease in the number of dugongs since the 1970s.

The mammal had been sought by hunters in the 20th Century for its meat, skin, and  bones. With a significant decline in the population, the mammal has been declared a Grade 1 National Key Protected Animal since 1988 by the Chinese State Council. There has been no verified dugong sightings by scientists since 2000.

The research was done by a team of international scientists who conducted interviews in 66 fishing communities across four Chinese provinces along the coastal region of the South China Sea.

Fishing, ship strikes, and human-caused habitat loss have resulted in the rapid decrease in the number of dugongs since the 1970s.

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ACCORDING TO INTERNATIONAL UNION FOR CONSERVATION OF NATURE ,WHICH WILDLIFE SPECIES IS FACING EXTINCTION IN INDIA?

The International Union for Conservation of Nature says these wildlife species found in India are facing an extremely high risk of extinction in the wild.

FEW LEFT: The Gundia frog (Indirana gundia) is a resident of a patch of forest in the Western Ghats. As forests are cut down to make way for construction, this frog is slowly losing its home.

DOWNWARD SPIRAL: The population of red-headed vultures has decreased by over 90% in just 10 years. Most of the birds died after feeding on the carcasses of livestock treated with diclofenac, a non-steroid painkiller used by farmers and veterinarians.

POSITIVE NOTE: The gharial (Gavialis gangeticus) was once found across Bangladesh, Bhutan, India, Myanmar, Nepal and Pakistan. It currently survives in several severely fragmented populations in India and Nepal. Conservation programmes in India are slowly improving numbers.

DEEP TROUBLE: The Indian swellshark (Cephaloscyllium silasi) is found in the western Indian Ocean. Their numbers are falling due to overfishing.

LOST RODENT: Sightings of the Large Rock Rat, also known as the Elvira Rat, are so rare that there are few photographs of them. This is an illustration of the species (Cremnomys elvira) by the Zoological Survey of India.

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WHY IS THE FORESTS OF THE MARINE WORLD UNDER THREAT?

A type of algae, kelp is crucial for thriving ecosystems the world over. However, kelp forests are shrinking. But, why? Let’s find out

Most types of seaweed or marine algae grow along the coasts in shallow waters, where they can attach themselves to rocks, shells, or the sea floor. A root-like part called holdfast anchors them firmly and prevents them being washed away by strong waves or currents. A soft, flexible stem-like frond with outgrowths similar to leaves emerges from the holdfast. Though they carry out photosynthesis, algae are not plants as they don’t have true roots, stems, leaves, or flowers. Marine algae can be green, brown, or red in colour. Red algae are delicate and feathery and prefer warm tropical seas. Small green algae are found everywhere in shallow waters. Brown algae called giant kelp grow in cool waters at depths ranging from 15 to 40 mt.

Extraordinary ecosystem

A kelp forest is one of the most valuable and productive: ecosystems on Earth. Kelp forests are found all over the world-the west coasts of North and South America, the southern tip of Africa and Australia, and off islands near Antarctica. In North America, kelp forests are found on the Pacific Coast from Alaska to California. A forest of kelp is home to a variety of creatures. They live and forage for food among its broad blades. The kelp provides shelter not only from predators. but also from storms. Mammals and birds that thrive in kelp forests include seals, sea lions, whales, sea otters, gulls, terms, egrets, and herons. Sea otters have an especially beneficial bond with kelp. Mother otters wrap their babies in kelp to keep them from drifting away while they go hunting. Adult otters also find the dense kelp canopies a secure place to snooze. The otters return the favour by eating sea urchins that dine on kelp. Kelp forests can shoot up in no time, growing up to 30 cm a day. Some species attain heights of over 45 mt!

Kelp farming is a big part of the billion-dollar global seaweed-farming industry. Kelp renders sea water less acidic. This enables kelp farmers to raise shellfish, which require low acidity. Kelp and mussels are grown on floating ropes, which also support baskets of scallops and oysters. One kelp farm can produce 40 metric tonnes of kelp and a million shellfish per hectare per year! As with other species of seaweed, kelp is used in many products,) including shampoos and toothpastes, as well as a wide range of foods such as salad dressings, puddings, cakes, dairy products, and ice cream. It is also employed in pharmaceuticals and in the manufacture of fireproof and waterproof textiles.

Urchin attack

The waters off the coast of northern California are home to lush forests of bull kelp. Since 2013, the population of purple sea urchins that feast on the kelp, has exploded, destroying almost 90 % of the kelp forest. Sea stars prey on purple urchins and keep their numbers in check. However, a mysterious disease killed off huge numbers of sea stars, leaving sea urchins to thrive. Sea snails (called red abalone) and red sea urchins, both of which are raised for meat and feed on bull kelp, died from starvation. Commercial red sea urchin and red abalone fisheries located on America’s northwestern coast have closed down as a result.

Fact file

• Kelp forests are the ocean’s lungs just as trees are the Earth’s lungs. They absorb carbon dioxide and give out oxygen.

• Warming seas along the Australian coast have wiped out huge swathes of kelp forest.

•Extremely hot weather is harmful to kelp forests. Strong storms can wipe out large areas by uprooting the plants from the sea floor.

• There are 18 species of edible kelp, including kombu widely used in Japanese cuisine.

•Kelp is rich in calcium and Vitamin K.

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WHAT IS MEAN BY EXTINCTION?

The dying out or extermination of a species is what is referred to as extinction. When species are diminished because of environmental factors or because of evolutionary changes in their members, extinction occurs. While rates of extinction have varied largely, human activities, deforestation, habitat loss, over-hunting, pollution and climate change have meant that the present-day extinction rate is many times more than what it was previously.

About 541 million years ago, a great expansion occurred in the diversity of multicellular organisms. Paleobiologists, scientists who study the fossils of plants and animals to learn how life evolved, call this event the Cambrian Explosion. Since the Cambrian Explosion, there have been five mass extinctions, each of which is named for the geological period in which it occurred, or for the periods that immediately preceded and followed it.

The first mass extinction is called the Ordovician-Silurian Extinction. It occurred about 440 million years ago, at the end of the period that paleontologists and geologists call the Ordovician, and followed by the start of the Silurian period. In this extinction event, many small organisms of the sea became extinct. The next mass extinction is called Devonian extinction, occurring 365 million years ago during the Devonian period. This extinction also saw the end of numerous sea organisms.

The largest extinction took place around 250 million years ago. Known as the Permian-Triassic extinction, or the Great Dying, this event saw the end of more than 90 percent of the Earth’s species. Although life on Earth was nearly wiped out, the Great Dying made room for new organisms, including the first dinosaurs. About 210 million years ago, between the Triassic and Jurassic periods, came another mass extinction. By eliminating many large animals, this extinction event cleared the way for dinosaurs to flourish. Finally, about 65.5 million years ago, at the end of the Cretaceous period came the fifth mass extinction. This is the famous extinction event that brought the age of the dinosaurs to an end.

In each of these cases, the mass extinction created niches or openings in the Earth’s ecosystems. Those niches allowed for new groups of organisms to thrive and diversify, which produced a range of new species. In the case of the Cretaceous extinction, the demise of the dinosaurs allowed mammals to thrive and grow larger.

Scientists refer to the current time as the Anthropocene period, meaning the period of humanity. They warn that, because of human activities such as pollution, overfishing, and the cutting down of forests, the Earth might be on the verge of—or already in—a sixth mass extinction. If that is true, what new life would rise up to fill the niche that we currently occupy?

Credit : National geographic 

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WHAT SPECIES ARE ON THE BRINK OF EXTINCTION?

Can you believe that at least one in five reptile species in the world are threatened with extinction? Yes, that is what the first major global assessment of the world’s cold blooded creatures reveals. Let’s look at the findings.

At least one in five reptile species are threatened with extinction, including more than half of turtles and crocodiles, according to the first major global. assessment of the world’s so-called cold-blooded creatures.

Catastrophic declines in biodiversity across the world are increasingly seen as a threat to life on Earth- and as important as the interrelated menace of climate change.

Threats to other creatures have been well documented. More than 40 percent of amphibians, 25 percent of mammals and 13 percent of birds could face extinction. But until now, researchers did not have a comprehensive picture of the proportion of reptiles at risk.

HOW MANY SPECIES ASSESSED

In a new global assessment. published in the journal Nature, researchers assessed 10,196 reptile species and evaluated them using criteria from the International Union for Conservation of Nature (IUCN) Red List of threatened species.

They found that at least 1,829. 21 per cent were either vulnerable, endangered or critically endangered. “It’s just overwhelming the number of species that we see as being threatened,” said co-author Neil Cox, who manages the IUCN-Conservation International Biodiversity Assessment Unit and co-led the study. “Now we know the threats facing each reptile species, the global community can take the next step…. and invest in turning around the often too under-appreciated and severe biodiversity crisis.”

TOOK 15 LONG YEARS

Young said the reptile assessment. which involved hundreds of scientists from across the world, took around 15 years to complete because of a lack of funding.

“Reptiles, to many people, are not charismatic. And there’s just been a lot more focus on some of the more furry or feathery species of vertebrates for conservation,” he said. Researchers hope the new assessment will help spur international action to halt biodiversity loss. Almost 200 countries are currently locked in global biodiversity talks to try to safeguard nature, including a key milestone of 30 percent of Earth’s surface protected by 2030.

“Through work like this, we advertise the importance of these creatures. They’re part of the tree of life, just like any other and equally deserving of attention,” Young said.  AFP. Crocodiles and turtles were found to be among the most at-risk species, with around 58 percent and 50 percent of those assessed found to be under threat respectively.  Crocodiles are killed for their meat and to remove them from human settlements. Turtles are targeted by the pet trade and used for traditional medicine. The Komodo dragon of the Indonesian islands is threatened with extinction, researchers say.

WHERE ARE THEY FOUND?

Threatened reptiles were largely found concentrated in Southeast Asia, Western Africa, northern Madagascar, the Northern Andes and the Caribbean. Reptiles restricted to arid habitats such as deserts, grasslands, and savannas are significantly less threatened than those in forest habitats, the study says.

THE KING IS IN DANGER

Another well-known species at risk is the fearsome king cobra, the world’s largest venomous snake. It has been classified as vulnerable, indicating it is very close to extinction”, according to the research. “It’s a real iconic species in Asia and it’s such a shame that even widespread species such as this are really suffering and in decline”. Logging and deliberate attacks by humans were among the biggest threats to the snake.

WHAT ARE THE THREATS THEY FACE?

Agriculture. logging. invasive species and urban development were found to be among the threats to reptiles, while people also target them for the pet trade or kill them for food or out of fear.

Climate change was found to pose a direct threat to some 10 per cent of reptile species. Longer-term threats such as sea level rise, or indirect climate-driven dangers such as fire, and from things like disease also have an impact.

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WHY DO CREATURES GO EXTINCT?

Extinction is when an entire population of a particular creature disappears from Earth. Though it sounds drastic, extinctions are quite common in Earth’s history. Scientists believe that 99 per cent – over five billion species that ever lived – have become extinct since the beginning of life. This could have happened due to reasons of lack of food or disastrous events like asteroids hitting Earth. In recent times, the speed at which species are becoming extinct has increased due to human activity.

The most common cause of extinction is a sudden, serious change in a species’ habitat. A habitat is the surroundings in which an animal lives. Animals can rarely survive such sudden change. Their food supply may be wiped out. They may also lose shelter or other things that they need to survive.

Many things can change a species’ habitat. Floods, fires, droughts, volcanoes, and other natural events may be causes. People also change the environment in ways that drastically affect animals. People clear forests and drain wetlands. They build dams that disrupt the flow of rivers. They build cities on land that animals need to survive. They also create harmful pollution.

Some changes that cause extinction affect only a small area. Others are large enough to affect the entire world. A fire or other local event may cause the extinction of animals that live only in that region. A sudden change in the global climate might wipe out an animal species that lives in many parts of the world.

People can cause extinctions more directly as well. Some species have been hunted to extinction. The passenger pigeon is one example of this. Humans killed millions of the birds over many years. The last one died in the early 1900s.

Dinosaurs first appeared on Earth about 215 million years ago. They were the most important land animals for more than 150 million years. By 65 million years ago, however, the dinosaurs had died out.

Many scientists believe that a large asteroid, or rock from space, caused this mass extinction. When the asteroid hit Earth, the impact caused drastic changes. Thick dust and other materials blocked the sun. Temperatures dropped, and plants could not grow. The dinosaurs could not survive the cold temperatures and lack of food. But early species of birds and mammals did survive.

Credit: Kids Britannica

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